In a prospective study of 1,546 patients delivered by Caesarean section a wound infection developed in 146 (9.4%); the rate was significantly higher in clinic patients (15.8%) compared with private patients (6.0%). Elective operations resulted in a lower incidence of wound infection (7.9%) than emergency operations (12.3%). Other factors significantly associated with postoperative wound infection were: the number of vaginal examinations before surgery (p less than 0.05), duration of operation (p less than 0.005), vertical skin incision (p less than 0.05) and category of surgeon (p less than 0.001). In 56 patients for whom a past history was available, there was a record of a wound infection in 31 (55%). Clinic patients were over-represented in all situations predisposing to wound infection.