In the title monomeric trimethyl-tin(IV) isothio-cyanate-4,4-dimethyl-pyridine adduct, [Sn(CH(3))(3)(NCS)(C(7)H(10)N(2))], the Sn(IV) atom shows a trans-C(3)SnN(2) trigonal bipyramidal coordination. The Sn(IV) atom lies out of the equatorial plane by 0.033 (4) Å in the direction of the donor N atom of the N-heterocycle. The crystal studied was a non-merohedral twin with a minor component of 48.8 (2)%.