In the title compound, C21H21AsS3, the three benzene rings make dihedral angles of 88.41 (10), 87.75 (9) and 74.74 (10)° with each other. The methylsulfanyl groups are roughly coplanar with their attached benzene rings [C—S—C—C torsion angles = −7.6 (2), 11.2 (2) and 4.1 (2)°]. In the crystal, weak C—H⋯π interactions link the molecules.