Delayed primary wound closure was performed in 146 patients considered at risk of developing wound infection according to established criteria. These patients were matched individually for age, weight, diagnosis, and the use of prophylactic antibiotics with 146 patients undergoing immediate wound closure during the same time period. The matched pairs were subdivided into five categories depending on the indication for delayed closure; obesity, cancer, "above and below" procedure, infection, and opened bowel. In all categories the incidence of wound infection was significantly lower in the patients with delayed closure. The over-all infection rate was reduced from 23.3% in the control group to 2.1% in the study group. Hospital stay was unaffected. Delayed primary wound closure provides a safe, simple, effective means of reducing the incidence of wound infection.