THESE EXPERIMENTS were designed to test whether delayed primary wound closure would effect a significant reduction in the incidence of wound infection following abdominal operations (eg, intestinal anastomoses, gastric resections, operations on the biliary tract) which are potentially contaminated by bacteria. This technique was suggested by Coller and Valk1 22 yr ago in the treatment of contaminated civilian wounds and has been used extensively by military surgeons since World War I as a method of treating contaminated war wounds. In the present study, the incidence of wound infection following delayed primary closure of the skin and subcutaneous tissues was compared with that of wounds closed primarily. The patients were from a women's surgical ward at the Barnes Hospital during a period from July, 1960, through June, 1961. The study included 95 intra-abdominal operations. A simple, uncomplicated system of patient selection was used which decreed that all patients assigned an