In order to get good antitumor agents especially better than 5-fluorouracil, tegafur and 1-hexylcarbamoyl-5-fluorouracil (HCFU), fourty nine 1-carbamoyl-5-fluorouracil having aromatic ring were synthesized from 5-fluorouracil acid isocyanates or amines. Antitumor activity was tested in the L-1210 tumor system, and 5 compounds gave better value of therapeutic ratio than Ei-fluorouracil, tegafur, HCFU, 1-(4-Methoxybenzylcarbamoyl)-5-fluorouracil gave the best result.