Twenty-one infants from six to 52 days of age (mean 23.3 days) with osteomyelitis were studied between 1965 and 1977. The etiologic agents were group B streptococcus (8), staphylococcus aureus (6), gramnegative bacilli (4), Streptococcus pneumoniae (1), and unknown (2). Patients with group B streptococcal osteomyelitis were characterized by an uncomplicated neonatal course, single bone involvement with a predilection for involvement of the proximal humerus, and lack of inflammatory signs. In contrast, patients with osteomyelitis due to other organisms frequently had had manipulative procedures predisposing to infection and were more likely to have multiple bone involvement, fever, and leukocytosis at the time of diagnosis. Functional impairment was detected in only one of 17 patients evaluated a mean of 36 months after diagnosis.