The Sn atom in the title compound, [Sn(CH(3))(2)(NCS)(2)(C(20)H(14)N(4))], is N,N',N''-chelated by the terpyridine part of the N-heterocycle. The Sn atom exists in a trans-C(2)SnN(5) penta-gonal-bipyramidal geometry [C-Sn-C = 173.66 (8)°] with the methyl groups in axial and the N atoms in equatorial positions.