In perioperative chemotherapy the question arises if, and to what extent, irritations of the wound-healing process are to be expected, especially after plastic surgery. Our research on wound-healing irritations under bleomycin therapy has been conducted in animal experiments and has resulted in definite recommendations for perioperative management. Taking UMEZAWA's experimental work as a basis, it can be assumed that the bleomycin-inactivating enzyme activity in squamous-cell carcinoma is in direct quantitative proportion to the bleomycin effect on these tumors. In clinical and experimental studies the bleomycin-inactivating enzyme activities of different squamous-cell carcinomas of the oral cavity have been tested. A lower enzyme activity - and a good clinical effect - has been found in highly differentiated carcinomas than in less differentiated and anaplastic carcinomas, with a less good effect. Reports in the literature on vascular support in carcinomas of the oral cavity prompted us to conduct microangiographic studies. Diminished vascularization with avascular regions of different size was found in most of the cases. Differentiated, medullar carcinomas showed a worse supply of blood vessels than undifferentiated and infiltrating carcinomas. The special morphological structures and functional factors of the tumor blood supply of the oral squamous-cell carcinoma are discussed in regard to their relevance for chemotherapy.