Consistently classifying, defining, and distinguishing among the range of medical services provided today--from diagnoses to treatments--is critical for reimbursing providers and analyzing health care utilization, outcomes, and cost. Codes serve this role by assigning each distinct service a unique identifier. Health care providers, such as hospitals and physicians, report medical conditions and the health-related services they have provided to patients on medical records. In August 2000, the Department of Health and Human Services (HHS) adopted two standard code sets for reporting medical procedures: (1) the International Classification of Diseases, 9th Revision, Clinical Modification, Volume 3 (ICD-9-CM Vol. 3); and (2) the Current Procedural Terminology (CPT). Despite HIPAA's goals for administrative simplification, many representatives of the health care industry have expressed concern that the individual limitations of these code sets result in inefficiencies in record keeping and data reporting. GAO found that, given the 18-month time frame allotted to HHS under HIPAA for adopting standard code sets, ICD-9-CM Vol. 3 and CPT were practical options for HIPAA standard code sets despite some limitations. Both code sets meet almost all of the criteria for standard code sets recommended by HHS's HIPAA implementation teams. For example, they improve the efficiency and meet the needs of the health care industry, have low additional costs and administrative burdens associated with their implementation, and are consistent with other HIPAA standards. In addition, each of these codes sets meets a criterion for procedural code sets recommended by the National Committee on Vital and Health Statistics.