We investigated 57 patients with sickle cell anaemia (HbSS) and bone and joint changes. Osteonecrosis simulating a wide range of conditions was a common radiological feature, and osteomyelitis occurred in 61% of cases. Salmonella species were the commonest causative organisms, occurring in 71% of patients with osteomyelitis, although salmonella septic arthritis occurred in only two. The distinction between vaso-occlusive bone crisis and acute osteomyelitis was often difficult since the classical clinical and radiological features and laboratory findings also occurred in bone infarction, a common feature of the disease.