To investigate the risks of post-operative complications in HIV-positive mothers who undergo a caesarean section (CS) because the delivery cannot be safely accomplished by the vaginal route or to protect the infant from viral infection. In a multicentre study, we reviewed the incidence, and type of post-operative complications in 156 HIV-positive women who underwent a CS. These results were compared with those observed in an equal number of HIV-uninfected women who matched for the indication requiring a caesarean delivery, the stage of labour, the integrity or rupture of membranes, and the use of antibiotic prophylaxis. Seven teaching hospitals providing obstetrical care for mothers infected with HIV. We found that six HIV-infected mothers suffered a major complication (two cases of pneumonia, one pleural effusion, two severe anaemia, and one sepsis) compared with only one HIV-negative woman who required blood transfusion after surgery. Minor complications like post-operative fever, endometritis, wound, and urinary tract infections were significantly more frequent in HIV-positive women than controls. Multivariate analysis revealed that in HIV-infected women the only factor associated with a significant increase in the rate of complications was a CD4 lymphocyte count <200±106/l. The results of our study indicate that HIV-positive mothers are at an increased risk of post-operative complications when delivered by CS. The risk of post-operative complications is higher in HIV-infected women who are severely immunodepressed.