Our experience at the Ramathibodi Hospital with 20 infants and children who had Aeromonas septicemia is reviewed. Their ages were from 1 day to 14 years. Eighteen patients had underlying diseases: leukemia, 5; aplastic anemia, 4; cirrhosis, 2; thalassemia/hemoglobinopathy, 3; renal failure, 1; ileal perforation, 1; marasmus, 1; and cavernous hemangioma with thrombocytopenia, 1. Blood cultures yielded Aeromonas hydrophila in all patients, and four patients had polymicrobial bacteremia. Fifteen episodes of septicemia were community-acquired and five were hospital-acquired. The clinical manifestations of these patients were similar to septicemia due to other Gram-negative enteric bacilli. Two patients each had ecthyma gangrenosum, necrotizing fasciitis and meningitis. Antibiotic treatment included penicillins, cephalosporins, aminoglycosides and sulfamethoxazole-trimethoprim. The overall case fatality rate was 50%; eight of the nine patients with acute leukemia or aplastic anemia died. With the exception of one child the blood cultures were sterile in all patients before death. Aeromonas septicemia is an uncommon but severe infection which occurs predominantly in compromised hosts.