Single and combination chemotherapies of VP 16-213, a new antitumor agent were evaluated for its antitumor effect against several murine tumors. Dose-dependent antitumor effects were observed when VP 16-213 was administered via any of the three routes, i.p., i.v. and orally, on days 1 and 5 after i.p. or s.c. inoculation of Ehrlich carcinoma and sarcoma 180. The drug also proved effective against i.v. inoculated EL-LP-12 (subline of Ehrlich carcinoma), i.p. or s.c. inoculated P388 and B16 melanoma, i.p. inoculated colon 26, and s.c. inoculated colon 38 and Lewis lung carcinoma. However, oral administration of the drug was not effective against B16 melanoma, colon 26 and Lewis lung carcinoma despite the fact that the doses employed for this route was higher than those employed for i.v. and i.p. routes. The optimum dosing schedule was also investigated with oral administration of the drug against s.c. inoculated Ehrlich carcinoma. A single dose (day 1) or two doses (days 1 and 5) were more effective than three doses (days 1, 3 and 5) or five consecutive daily doses. VP 16-213 showed additive and more than additive effects in combination with the antitumor agents, cyclophosphamide, BCNU, mitomycin C or cisplatin against s.c. inoculated Ehrlich carcinoma and i.v. inoculated EL-LP-12.