Physicians' Current Procedural Terminology (CPT) is the system most commonly recognized by third-party payers for describing medical services in numerical codes for subsequent reimbursement. Adequate description of psychiatric services using CPT codes is an ongoing challenge. Psychiatrists have responded to the demands of third-party payers and peer review organizations for documentation and accountability by billing for specific services rather than by designating all care as psychotherapy. The authors present guidelines for using CPT codes to describe inpatient and outpatient psychiatric services and consultation. They also discuss continuing controversies, including regional diversity in the interpretation of codes by third-party payers, the risks of "gaming" the coding process, and the use of CPT codes by nonphysician providers and the consequent mixing of data on service charges.