The pentanoyl group and the 5-fluorouracil moiety of the title compound, C9H11FN2O3, are essentially coplanar, with the pentanoyl carbonyl group oriented towards the ring CH group and away from the nearer ring carbonyl group. In the crystal structure, two inversion-related molecules form a dimer structure, in which two N—H...O hydrogen bonds generate an intermolecular R22(8) ring. In addition, there are intra- and intermolecular C—H...O interactions.