The ICD-9-CM was an adaption maintained by the Centers for Medicare and Medicaid Services (CMS) that was used for assigning diagnostic codes associated with inpatient, outpatient, and physician office utilization. The ICD-9-CM codes have three to five numeric characters, with the exceptions of the V codes, E Codes and M Codes that begin with a single letter.

The legacy ICD-9-CM system lacked the specificity needed to determine an exact diagnosis as the ICD-9 codes can be very broad and it became difficult to compare costs, treatments, and technologies. For that reason the ICD-9 code set was deprecated and replaced on September 30, 2015 by ICD-10 codes.

The last version of ICD-9-CM had 14,567 diagnosis codes in 20 different categories. The List of ICD-9 codes included codes for the following:

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