The dibutyltin(IV) oxide complex reacts with 5-fluorouracil-1-propanonic or5-fluorouracil-1-acetic acid to give the potential antitumor activity complexes [( 5-fluorouracit)-1-(CH2)(m)COOSn (Bu-n)(2)](4)O-2 m = 1, (1); m = 2, (2)] which were determined by IR and H-1 NMR. The crystal structure determination shows that complex 2 is a dimmer, in which two [(5-fluorauracil)-1-CH2CH2COOSn (Bu-n)(2)](2)O units are linked by bridging oxygen atom, and the tin atoms adopt distorted trigonal bipyramids via two carbons from dibutyl group and three oxygen atoms from 5-fluorourateil and bridging oxygen. In vitro test shows complexes 1 and 2 exhibit high cytotoxicity against OVCAR-3 and PC-14.