Upper extremity disorders (UEDs) account for a significant number of work-related illnesses in the US workforce. Little information exists on the distribution of UEDs, their associated health care and indemnity costs, or patterns of work disability. The study presented is an analysis of upper extremity claims within the federal workforce. In this study, the universe consisted of all claims accepted by the US Department of Labor, Office of Workers' Compensation Programs (OWCP), from October 1, 1993, through September 30, 1994. A total of 185,927 claims of notices of injury were processed during the study period, and of these, 8,147 or 4.4% had an UED diagnosis coded according to the International Classification of Diseases, Clinical Modification (ICD-9-CM). 5,844 claims involved a single UED diagnosis and were the only claims filed by these employees between October 1, 1990, and September 30, 1994. These single claims with single diagnoses comprised the sample for further analysis. Mononeuritis and enthesopathies of the upper limb were the most common diagnoses, accounting for 43% and 31% of the claims, respectively. Women had a higher proportion of carpal tunnel syndrome, "unspecified" mononeuritis, and "unspecified" enthesopathies. The majority of claimants for both the mononeuritis- and enthesopathy-related diagnoses were between 31 and 50 years of age, received only health care benefits, and did not incur wage loss. Health care costs for mononeuritis and enthesopathy claims were $12,228,755 (M = $2,849). Carpal tunnel syndrome(CTS) and enthesopathy of the elbow were the most costly diagnoses, accounting for 57% and 16% of the total, respectively. Surgical services represented the highest expenditures in CTS claims. Physical therapy accounted for the majority of health care costs for enthesopathy cases. The mean number of workdays lost for CTS and enthesopathy claims were 84 and 79, and the average indemnity costs were $4,941 and $4,477, respectively. These findings indicate that while UEDs represent a relatively small percentage of all workers' compensation cases, the health care and indemnity costs are considerable. Also mean duration and pattern of work disability revealed that these disorders can result in chronic work disability similar to that observed in low back pain. The results highlight the need to determine whether interventions that account for the majority of costs significantly impact long-term outcomes. There is also a need to identify risk factors for prolonged disability in those who experience problems with delayed recovery.