Bacterial superinfection is one of the major complications leading to death in patients with visceral leishmaniasis. We studied the frequency and type of bacterial infection in 54 patients admitted to hospital with visceral leishmaniasis. The patients were children who ranged in age from 3 1/2 months to 7 years. Bacterial infections were found in 22 (41%) of the patients. Bacteria were isolated in patients with pneumonia, septicaemia, otitis media, urinary tract infections and skin infections. Enterobacteriaceae were the most common bacterial agents isolated. In infants with visceral leishmaniasis, fatal bacterial infections can be accompanied by nonspecific signs and symptoms. Thus, it is important to initiate antibiotic treatment early.