Flavone acetic acid, given on Days 2 and 9 at a dose of 267 mg/kg, inhibited tumor growth completely in 60%-80% of mice with early-stage Colon Adenocarcinoma 38. The therapeutic efficacy of the flavone against this tumor was retained when the sites of tumor implantation and drug administration were separated. Flavone acetic acid also caused regression of advanced (500-mg) Colon 38 tumors, with greatest efficacy observed following administration of high individual dose rather than high total dose. Unlike many previous potential anticancer agents, only modest activity was observed for this compound against either P388 or L1210 leukemia.