1. A series of 328 cases of acute haematogenous osteomyelitis in children is analysed.

2. In the first group ofseventy-seven cases from 1944 to 1950 penicillin gave excellent results.

3. After 1950 the disease took on new characteristics in terms of frequency, severity and age incidence, with the appearance of a staphylococcus resistant to penicillin: 251 cases are recorded from 1951 to 1960.

4. The importance of the early assessment ofthe disease into degrees of severity is emphasised as the surgeon's guide in his form of management.

5. The value of operative decompression is discussed.

6. The frequent and dire consequences of hip joint involvement are analysed and draillage of the hip joint is described.