Musculoskeletal infections constitute an unusual clinical manifestation in patients with human immunodeficiency virus (HIV) infection. Available information about patients' characteristics and their clinical course has been obtained mainly from case reports and small retrospective studies. Our retrospective study is the largest in the literature providing detailed information about the clinical and laboratory characteristics of HIV-infected patients with different musculoskeletal infections. We identified 30 patients with various infections of the musculoskeletal system during a 5-year period among a cohort of 3,000-4,000 HIV-infected patients, and we describe them along with all cases of musculoskeletal infections in patients with HIV reported in the literature since 1985. Septic arthritis was the most commonly reported infection of the musculoskeletal system. It usually affects young men with a median CD4 count of 241. The exact contribution of a previous history of intravenous drug abuse in the pathogenesis of septic arthritis is unclear from the present and previous studies. Staphylococcus aureus was the most commonly isolated agent (31.3%). Numerous atypical pathogens were also identified as causes of septic arthritis. Approximately 90% of patients recovered with appropriate antibiotic treatment. Osteomyelitis was a more serious infection which also affected young individuals but with lower CD4 counts (median, 41). Half the cases were due to atypical mycobacteria. The mortality rate in the previously reported cases and in our series was high (20%). Pyomyositis is an increasingly recognized infection of the striated muscles in HIV-infected patients. It affects almost exclusively males with advanced HIV infection (median CD4 count, 24). Most cases are due to Staphylococcus aureus (67%). Drainage of the involved muscle(s) accompanied by proper antibiotic treatment resulted in resolution of the infection in the majority of patients (90%). Although the incidence of musculoskeletal infections in patients with HIV from this and previous studies appears to be low (0.3%-3.5%), these infections add a significant morbidity and mortality in the affected individuals. Better understanding of their pathogenesis and clinical course would aid the proper diagnosis and management of these infections.