Dicyclohexyltin(IV) bis(2-pyridylthiolate), compound 1, crystallizes in the orthorhombic system, a = 16.448(3), b = 40.315(8) and c = 7.113(3). Its molecular structure is best described as a tetrahedron, based on the two carbon-tin and the two sulfur-tin bonds, which is however strongly distorted as a consequence of two weak additional nitrogen-tin bonds. Compound 1 and four other diorganotin(IV) bis(2-pyridylthiolates) are characterized by Mossbauer, H-1, C-13 and Sn-119 NMR spectroscopy, and by FAB mass spectrometry. Their in vitro antitumour activity against two human tumour cell lines, MCF-7 and WiDr is reported. The ID50 values found are comparable to those found for cis-platin, but deceptively higher than for many other diorganotin compounds.