The purpose of the study was to evaluate the history, clinical picture and diagnostic difficulties of acute haematogenous osteomyelitis (AHOM) in children. Forty-seven children under the age of 15 with bacteriologically proven AHOM were collected prospectively in Finland in 1981-93. Staphylococcus aureus was responsible for 89% of the cases. The commonest sites affected were the tibia (25%) and the femur (23%) followed by the pelvis (15%) and the calcaneus (11%). Sites other than the long bones increased in frequency in children over the age of 4 years. Most of the children came with a history of a week or less with classic signs and symptoms of AHOM, increased C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) values but negative X-rays. Delay in hospital admission was observed in 19%. In 11% antimicrobial therapy was not instituted within 48 hours on ward. All children were clinically healthy at the 1-year check-up with minor X-ray changes seen in 11 patients. We conclude that children in Finland seek treatment early in the course of AHOM and have a good outcome. S. aureus is the main aetiological agent affecting primarily the long bones, but in older children pelvic and calcaneic sites are also frequent. No significant delays affecting the outcome were noticed in admittance to hospital or in the diagnosis of AHOM.