TNF, IFN, LT and IL-1 are well-known biological response modifiers (BRM) with cytocidal activity. Whereas carcinostatic agents generally derive their cytocidal action from their direct mutual reaction with target molecules (e.g., DNA, RNA), the cytocidal action of BRM resides in the enzyme response which ensures upon their binding to receptors. Accordingly, concomitant use of these drug of differing mechanism of action has a rationale. Considering that a certain kind of counteracting protein is present in cancer cells which are refractory or resistant to such cytokines, combination therapy with carcinostatic agents with inhibitive activity against such protein is also justified. In the same context the effects of TIL and LAK activated by IL-2 could be enhanced if the immune system should be modulated by combined use of BRM and carcinostatic agents such as CY. This paper discusses the results obtained with BRM and carcinostatic agents in combination in animal models and clinical cases.