BACKGROUND The peritoneal spread of cancer is a well-known entity carrying a dismal prognosis. A new therapeutic approach is the combination of cytoreduction with heated intraperitoneal chemotherapy (HIPC). The risk of an intra-abdominal anastomosis in the presence of such chemotherapy is recognized clinically but the experimental data on the subject are lacking. The aim of this study is to examine the influence of chemotherapy and hyperthermia on the healing of colonic anastomosis. METHODS Colonic anastomosis were performed in four groups of male Wistar rats: (1) control (operation only), (2) HIPC with saline, (3) with mitomycin C (MMC), and (4) with cisplatinum. HIPC was performed using a closed circulation system at 40 degrees C over 20 min. Anastomotic strength was tested on day 4, 7, 10, and 21. RESULTS The bursting pressure of anastomoses in rats treated by HIPC was significantly lower than in controls. On day 4, it was 54.8 mm Hg, 38 mm Hg, 18 mm Hg, and 14.8 mm Hg in groups 1-4, respectively, while on day 7 it was 170 mm Hg, 188 mm Hg, 83 mm Hg, and 19 mm Hg, respectively (P < 0.01). The difference decreased on day 10 and almost vanished on day 21. HIPC with cisplatinum had the worst effect on anastomotic healing during the early postoperative period. CONCLUSIONS Cytoreduction and HIPC are gaining popularity. However, the use of heated chemotherapy has a detrimental effect on the strength of colonic anastomosis, especially during the early postoperative period (until day 10). This may cause anastomotic failure and postoperative morbidity. Therefore, careful selection and avoidance of unnecessary anastomoses are mandatory.