Reaction of mepirizole (M) with diorganotin(IV) dihalides yielded compounds of type [SnR2X2(M)] (R, X = Et, Cl; Et, Br; Bu, Cl; Bu, Br; Ph, Cl). The structure of dichlorodiphenyl(mepirizole)tin(IV) was determined by X-ray diffractometry. The crystal consists of discrete [SnPh2Cl2(M)] units in which an N,N′-bidentate mepirizole, the trans phenyl rings and the cis chlorine atoms define a pseudo-octahedral coordination polyhedron around the tin atom. Mössbauer and vibrational spectroscopic data suggest similar structures for the other compounds prepared. The 1H NMR spectra show that the mepirizole ligand is largely dissociated in CDCl3. The most active compounds against the human carcinoma cell line KB were the butyl derivatives.