International Classification of Diseases, Clinical Modification (ICD-9-CM) is a classification used in assigning codes to diagnoses associated with inpatient, outpatient, and physician office utilization in the U.S. The ICD-9-CM is based on the ICD-9 but provides for additional morbidity detail and is annually updated on October 1. It was created by the U.S. National Center for Health Statistics as an extension of ICD-9 system so that it can be used to capture more morbidity data and a section of procedure codes was added.

It consists of several volumes. The National Center for Health Statistics (NCHS) and the Centers for Medicare and Medicaid Services are the U.S. governmental agencies responsible for overseeing all changes and modifications to the ICD-9-CM.