We studied severe infections which occured in 51 liver transplant recipients between july 1986 and december 1989 (age range 4-67 years). The overall mortality was 18/51 (35,3%) and 6 deaths were due to infection; 4 patients underwent a second transplant procedure because of recurrence of hepatitis B. All patients received an antimicrobial prophylaxis (piperacillin +/- teicoplanin IV for 48 h +/- oral nystatin +/- oral norfloxacin for 15 days). 38/51 patients had a severe infectious episode, 14 due to one type of micro-organism, 20 due to two types, 4 due to three types (bacterial +/- viral +/- fungal). 66% of the episodes of infection occured in the first month and 97% in the first three months after transplantation. Of the 112 infections, 69 (61,6%) were bacterial: 28,6% due to Gram positive bacteria (23,2% due to Staphylococcus), 29,4% due to Gram negative bacteria (9,8% due to Pseudomonas) and 3,6% due to anaerobic organisms. 37/112 (33%) were viral infections (14,3% due to Cytomegalovirus) and 6/112 (5,4%) were fungal. Among the 139 locations, 42 (30,2%) were bacteriemia, viremia or fungemia, 18 (12,9%) were soft tissue manifestations, 15 (10,8%) were hepatitis, 13 (9,3%) were pneumonia, 12 (8,6%) were cholangitis, 11 (7,9%) were oropharyngeal. 10 (7,2%) were peritonitis and 6 (4,3%) involved digestive mucosa.