Fifty-one gastric adenocarcinoma patients were divided into two groups, according to the route of administration of the anticancer drug. One group was given FT-207 (tegafur, an enteric coated granule) orally and the other group, FT-207 in the form of a suppository. Blood and tissue concentrations of the drug were examined after a three-day administration of 750 mg at 09.00 and 21.00 hours. There were no significant differences between the two groups with respect to the concentrations of FT-207 and its metabolite 5-FU in the tissues. Levels of 5-FU in the excised tumor averaged 0.256 and 0.160 micrograms/g, in oral and rectal administrations, respectively, and levels in normal lymph nodes averaged 0.174 and 0.179 micrograms/g, respectively. The difference in 5-FU levels between normal and tumor tissues was statistically significant (P less than 0.05).