Cell ingrowth, hydroxyproline accumulation, and mRNA expression of collagen I were measured in two polytetrafluoroethylene grafts implanted subcutaneously at the time of colorectal cancer surgery to evaluate the influence of early postoperative chemotherapy on human wound healing. Eleven patients treated with intraperitoneal 5-fluorouracil and intravenous folinic acid Days 1-6 after operation were compared with 15 patients who underwent surgery alone. At 1 week, chemotherapy-treated patients had accumulated less hydroxyproline (mean 0.35 +/- 0.33 micrograms/cm) compared with untreated patients (mean 0.73 +/- 0.37 micrograms/cm, P < 0.05). By 2 weeks, the hydroxyproline content had increased sixfold in the chemotherapy group (P < 0.01) and threefold in the nonchemotherapy group (P < 0.01) and there was no difference between the groups. Cell and connective tissue ingrowth and total RNA content did not differ between the groups at any point in time, but at 1 week the mRNA expression of collagen I was higher in the chemotherapy group (P < 0.05). These results indicate that collagen accumulation in human subjects is reduced during a short course of postoperative chemotherapy and normalizes after the end of treatment.