Abstract Diethyl-and di-n-butyltin (IV) oxides react with 3-amino-4-methylbenzoic acid in a 1: 2 (a) and 1: 1 (b) molar ratio to yield dialkyltin compounds of the types R 2 Sn [O 2 CC 6 H 3- 3-NH 2-4-CH 3] 2 (a) and {[R 2 Sn (O 2 CC 6 H 3-3-NH 2-4-CH 3)] 2 O} 2 (b). The compounds obtained were characterized by 1 H, 13 C, 119 Sn NMR and by Mössbauer spectroscopy. Compound 1a was tested in vitro against two human tumor cell lines, MCF- ...