From 1976 to 1981, 28 episodes of group B streptococcus (GBS) septicemia were identified in our hospital (CHUV, University Hospital Lausanne), 18 in 17 adults and 10 in newborns. The latter had acute respiratory distress syndrome (8 cases) or meningitis (2 cases). In adults the skin was the main source of infection (6 diabetic foot, 4 acute cellulitis complicating chronic skin diseases, 2 infections secondary to diagnostic procedures (capillary and ascitic taps) and 1 meningitis secondary to neurosurgery). The other sources of infection were 1 pharyngitis, 1 pneumonia and 1 pyelonephritis. Eleven patients had an underlying disease (7 diabetes and 4 malignancies). Four patients developed septic osteoarticular metastases, one after a 3 weeks' course of antibiotic. In the latter case, as well as in the two adult patients who died, the strains of GBS were found to be tolerant to penicillin. Thus, GBS septicemia are not rare in adults and occur often in compromised hosts such as diabetics. The portal of entry is frequently the skin and the course may be severe with distant complications.