advanced metastatic disease of solid tumors, dictates that each tumor mass, indeed each individual metastasis, will have a unique antigen and cytokine environment and hence unique response to immune modu­ lation. A differential response to immunotherapy is thus inevitable. 4. Many of the human trials described are not randomized and report survival or response against historical controls. Most tumors described are immunogenic human tumors: renal cell cancer and melanoma are most common. In order to avoid the well-described inter-patient vari­ ation and rare incidence of spontaneous response among patient samples as well as selection bias and changes in practice over time, randomized trials are required. 5. Immunological treatment is unlike conventional chemotherapy in its endpoint. Most chemotherapeutic regimes require a complete response or a good partial response for cure or good palliation. There are now many cases where immunotherapy has provided long-term palliation without massive tumor reduction. Immunity may be stimulated to a degree which holds tumorigenicity in check and most importantly, pro­ vides good palliation for the patient in a manner that differs essentially from chemotherapy.