Twenty new dipeptide 5-fluorouracilpropyl and -butyl ester hydrochlorides were prepared from 5-fluorouracilpropyl or -butyl esters of amino acids with N-protected amino acid anhydrides. The antitumor activities of five of them were tested against Ehrlich ascites carcinoma in mice. Phe-Gly-O-(CH2)3-5-fluorouracil and Val-Leu-O-(CH2)4-5-fluorouracil hydrochlorides showed an inhibition ratio of 89.4% and 86.8%, resp.