2027 ICD-10-CM Diagnosis Code Z51.11Encounter for antineoplastic chemotherapy

ICD-10-CM Codes›Z00–Z99›Z40-Z53›Z51

ICD-10-CM Z51.11
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Z51.11 is a billable ICD-10-CM diagnosis code for encounter for antineoplastic chemotherapy. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 826 through 830, 837 through 839, 846 through 848. The code is exempt from POA reporting. Coders also document this condition as chemotherapy changed - patient choice. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Encounter for antineoplastic therapies.

Code Identity

ICD-10-CM Code
Z51.11
Billable Status
Yes — Valid for Submission
Code Describes
Encounter for antineoplastic chemotherapy
Short Description
Encounter for antineoplastic chemotherapy
Same as the full description in the CMS dataset.
Parent Code
Z51.1
Encounter for antineoplastic chemotherapy and immunotherapy

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ40-Z53Encounters for other specific health care
CategoryZ51Encounter for other aftercare and medical care
This CodeZ51.11Encounter for antineoplastic chemotherapy

Present on Admission (POA)Billing

Z51.11 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Encounters for other specific health care (Z40-Z53).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Chemotherapy changed - patient choice
  • Chemotherapy changed - progressive disease during chemotherapy
  • Chemotherapy changed - technical or organizational problems
  • Chemotherapy prior to lymphadenectomy
  • Chronic disease - treatment changed
  • Reason for change in planned chemotherapy treatment

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Z51.11: its own notes plus those printed at Z51.1, Z51, block Z40-Z53, and Chapter 21. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Z51 Encounter for other aftercare and medical care applies to 8 codes
  • follow-up examination after treatment (Z08-Z09)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Z51.1 Encounter for antineoplastic chemotherapy and immunotherapy applies to 2 codes
  • encounter for chemotherapy and immunotherapy for nonneoplastic condition - code to condition
From Block Z40-Z53 Encounters for other specific health care applies to 164 codes
  • follow-up examination for medical surveillance after treatment (Z08-Z09)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From Z51 Encounter for other aftercare and medical care applies to 8 codes
  • condition requiring care

Notes

General instructions on how these codes are used.

From Chapter 21 (Z00-Z99) Factors influencing health status and contact with health services applies to 1,425 codes
  • Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
  • (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination (immunization), or to discuss a problem which is in itself not a disease or injury.
  • (b) When some circumstance or problem is present which influences the person's health status but is not in itself a current illness or injury.

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name Z51.11, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming Z51.11: they are not reported together with it, unless the two conditions are unrelated.

  • Z08 Encounter for follow-up examination after completed treatment for malignant neoplasm
    aftercare following medical care (Z43-Z49, Z51) names Z51, which includes this code
  • Z09 Encounter for follow-up examination after completed treatment for conditions other than malignant neoplasm
    aftercare following medical care (Z43-Z49, Z51) names Z51, which includes this code

Excludes2 1

These codes carry an Excludes2 note naming Z51.11: its condition is not part of those codes, and both may be reported when the patient has both.

  • Z98 Other postprocedural states
    aftercare (Z43-Z49, Z51) names Z51, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR FAC006
Encounter for antineoplastic therapies
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Cancer Chemotherapy

Cancer chemotherapy is a type of cancer treatment. It uses medicines to destroy cancer cells.

The full article covers:

  • What is cancer chemotherapy?
  • What are the side effects of chemotherapy?
  • What can I expect when getting chemotherapy?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert Z51.11 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
V58.11 Antineoplastic chemo enc
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Z51.11Overview

What is the ICD-10 code for encounter for antineoplastic chemotherapy?

The ICD-10-CM code for encounter for antineoplastic chemotherapy is Z51.11 (sometimes written as Z5111). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Z51.11 (Encounter for antineoplastic chemotherapy and immunotherapy) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report encounter for antineoplastic chemotherapy on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Z51.11 group to?

When encounter for antineoplastic chemotherapy is the principal diagnosis on an inpatient stay, it groups to MS-DRG 837, 847, 827, 829, 839, 846, 838, 828, 826, 848, 830, with relative weights from 0.7752 to 4.7560 depending on complications. Higher weights mean higher Medicare reimbursement.

Is Z51.11 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for encounter for antineoplastic chemotherapy on inpatient claims. The code appears in the Encounters for other specific health care (Z40-Z53) range of the CMS exempt list.

What is the ICD-9 equivalent of Z51.11?

Under the General Equivalence Mappings, encounter for antineoplastic chemotherapy converts to ICD-9-CM V58.11 (antineoplastic chemo enc). The mapping is a direct match.