To study the incidence of shock in children in association with gram-negative bacillary (GNB) sepsis and Haemophilus influenzae type b sepsis, we reviewed all episodes of septicemia with those organisms in a 10-month period. GNB were isolated from 10.95% and H. influenzae b from 13.8% of the patients whose blood cultures yielded bacteria. Shock occurred in 12.5% of patients with sepsis caused by GNB and in 10.3% of those with H. influenzae b sepsis. Shock occurred more frequently in patients with H. influenzae b sepsis with meningitis (20.6%) and more commonly in those who had GNB sepsis without meningeal involvement (11.4%). GNB sepsis was associated with severe shock and caused death of three of the four patients. Only one of the five patients with shock caused by H. influenzae b had severe shock and died. The good outcome of patients with sepsis and shock caused by H. influenzae may be related to the health status before illness and prompt appropriate antibiotic therapy.