The antitumor effects of GANU have been examined in a panel of mouse tumors for which data appear to be lacking in the literature. GANU has significant activity against P388 leukemia and TLX5 lymphoma, and also against the solid tumors B16 melanoma and Lewis lung carcinoma; pulmonary metastases of this tumor are particularly sensitive to the effects of GANU. The effects of GANU on TLX5 lymphoma and Lewis lung carcinoma are less pronounced than those of BCNU and CCNU, as already reported for L1210 leukemia. In contrast with other results obtained with this tumor, chlorozotocin has a less pronounced effect than GANU, and virtually none in lung metastases of Lewis lung carcinoma.