A protocol of treatment for acute haematogenous osteomyelitis has been evaluated in 75 children. Intravenous cloxacillin and benzylpenicillin were given in hospital until the child had improved after which oral antibodies and immobilisation were continued at home for a total of six weeks. Oral cloxacillin was used most frequently as Staphylococcus aureus was the major pathogen. Simple drainage of subperiosteal pus was carried out in the 17 children with clinical evidence of an abscess. Ninety-two per cent of the 55 children with acute osteomyelitis diagnosed early were cured by a single course of antibiotics without an operation and with less than one week in hospital. Only 25 per cent of the 12 children with late-diagnosed acute osteomyelitis were cured with a single course of antibiotics and an operation. A longer period in hospital, a prolonged course of antibiotics, and secondary operations were required to cure the other children. Seven (88 per cent) of the eight neonates and infants with acute osteomyelitis were cured with a single course of antibiotics and an operation with only one to two weeks spent in hospital. The remaining infant was cured with a further course of antibiotics. The overall cure rate with a single course of treatment was 83 per cent, and the remaining children were cured with further treatment. More children would be cured with a single course of antibiotics and immobilisation without the need for surgical intervention if treated was started within one or two days of the onset of the illness rather than after four to five days when the disease is more advanced with the formation of and abscess.