One of the most important aspects of a medical facility is accurate medical coding for prompt reimbursement. Claims are placed electronically using the CMS-1500 health insurance claim form; however, choosing correct codes to describe services rendered is the initial and important part of this process. Coding translates descriptions of diseases, procedures, injuries, supplies, and other medical services into alphanumeric or numeric formats. Three coding systems are used here in the United States today and throughout most of the world to make these necessary decisions. It is essential to understand the human body and its functions in order to make the correct coding choices. This article describes briefly the three CPT, HCPCS and ICD-9-CM medical coding systemsCurrent Procedural Terminology