Risk factors associated with surgical infections are related to many events that modulate the immune system and affect the surgical procedure. The aim of this study was to determine the influence of low CD4+ lymphocyte counts in 24 patients with human immunodeficiency virus (HIV) undergoing abdominal surgery. Blood samples were obtained, and the lymphocyte population was evaluated perioperatively, as was the nutritional status of the patient. All the patients received selective antibiotic prophylaxis depending on the surgical procedure performed: (1) clean surgery: splenectomies (n = 8); (2) clean-contaminated: cholecystectomy and biliary tract surgery (n = 8); and (3) contaminated: appendectomy (n = 8). Depending on their CD4 count, two groups were formed: one with 200 to 500 cells/ml (n = 11) and the other with < 200 cells/ml (n = 13). When surgical infection was suspected, surgical drainage and microbiologic cultures were undertaken. For statistical evaluation of the groups ANOVA and the chi-square test were used; p < 0.05 was considered significant. Altogether 14 patients (58.3%) had a wound infection, and the mean (+/- SD) CD4 count in those patients was decreased (221.7 +/- 75.1) compared with that of the 10 patients in the uneventful group (386 +/- 81.2). Surgical infection rates were 50% for clean procedures, 62.5% for clean-contaminated procedures, and 62.5% for contaminated surgery. The group of patients with CD4 counts of < 200 cell/ml had an increased incidence of surgical infection, regardless of the type of surgery (p = 0.002). Thus the surgical infection rates with HIV patients undergoing abdominal surgery are dramatically increased. The CD4 and subsequently depressed neutrophil populations increase the risk of surgical infection during major procedures regardless of the type of surgery performed.