Human immunodeficiency virus (HIV) infection has radically changed African orthopaedic practice within a decade. In Lusaka, a third of adults are infected, but most have no physical signs of the disease. Early experience showed that closed fractures healed normally, the risk of sepsis during osteosynthesis was increased and most open fractures became septic. Major orthopaedic surgery in HIV-positive patients has increased risks of sepsis which rise steeply in those with physical signs of HIV disease. Musculoskeletal infections such as tropical pyomyositis, adult haematogenous long-bone osteomyelitis, and late haematogenous infection of implants, appear as immune competence wanes. There is a dual epidemic of tuberculosis and HIV, and bone and joint tuberculosis is now common. Atypical features suggest that traditional diagnostic criteria for spinal tuberculosis may be inadequate. Rheumatoid diseases, especially reactive arthritis, are common and serious complications of HIV disease. The risk of transmission of HIV between patient and surgeon is small, especially if recommended precautions are universally applied.