The therapeutic effects of orally administered menogaril, a semisynthetic analog of the anthracycline antibiotic nogalamycin, were studied on a panel of human stomach and breast cancer xenografts. The maximum tolerated dose (200 mg/kg) of menogaril was administered 3 times every 4 days and its growth-inhibitory effects on subcutaneously implanted tumors in nude mice were evaluated. Menogaril significantly retarded the growth of 3 out of 7 stomach cancers, SC-2, SC-9 and 4-1ST, and 3 out of 4 breast cancers, H-31, MC-2 and MX-1, with overall response rates of 43 and 75% for stomach and breast cancers, respectively. Some of these relatively responsive cancers were also treated by daily oral administration for 5 consecutive days, but the anticancer effects of the intermittent administration seemed to be better. These results suggest that menogaril may be effective against stomach and breast cancers when orally administered.