We reviewed the records of fifty-five children, including eleven infants (three of whom were neonates), who had at least one skeletal manifestation of hematogenous osteomyelitis. Forty-two of the patients were boys and thirteen were girls. The patients were classified into three groups: those who had early acute, those who had late acute, and those who had chronic osteomyelitis. This classification system was based on clinical and radiographic criteria. Seven patients had early acute osteomyelitis; eighteen, late acute osteomyelitis; and thirty, chronic osteomyelitis. The bones most often affected were the tibia (twenty-two patients) and the femur (nineteen patients). Penicillin-resistant Staphylococcus aureus grew on culture of specimens of purulent material from twenty-nine (76 per cent) of thirty-eight patients. Escherichia coli, Proteus mirabilis, and Enterobacter grew on culture of specimens of purulent material from one patient each. Six cultures showed no growth. No purulent material was obtained from seventeen of the fifty-five patients. The seven patients who had early acute osteomyelitis, and four of the eighteen patients who had late acute osteomyelitis, responded well to antibiotic treatment only. A combination of antibiotic and operative treatment was needed in fourteen of the eighteen patients who had late acute osteomyelitis and in all thirty patients who had chronic osteomyelitis. Forty-nine of the fifty-five patients were followed for two years; the remaining six patients were lost to follow-up. The two-year results were good in nineteen of the twenty-three patients who had acute (early or late) osteomyelitis and in fifteen of the twenty-six patients who had chronic osteomyelitis.(ABSTRACT TRUNCATED AT 250 WORDS)