Antineoplastic drugs, given in the perioperative period, are thought to be a hazard to wound repair. Since fibroblast collagen synthesis is crucial to healing, we examined the effects of bleomycin, cisplatin and 5-fluorouracil on collagen synthesis in confluent cultures of fibroblasts from human colon and skin. The drugs were added in final concentrations between 0.1 and 50 microM. Bleomycin did not affect collagen synthesis in colon fibroblasts but inhibited synthesis in skin fibroblasts. Collagen synthesis in colon fibroblasts was strongly, and specifically, inhibited by cisplatin while synthesis in skin fibroblasts was affected only slightly. 5-Fluorouracil had no effect whatsoever on the collagen synthetic capacity in either colon or skin fibroblasts. If skin fibroblasts were cultured in the presence of transforming growth factor beta (TGF beta), the antineoplastic agents inhibited the TGF beta-stimulated collagen synthesis at far lower concentrations than those needed to suppress non-stimulated synthesis. This effect was not observed in fibroblasts from colon. The possible implications of these observations, as pertain to the use of perioperative chemotherapy, are discussed. Since 5-fluorouracil did not directly affect collagen synthesis in colon fibroblasts under any of the conditions tested it is suggested that the data support the contention that this drug is relatively harmless for intestinal healing.