The crystal structure of the title triangulo-triruthenium compound, [Ru(3)(C(21)H(21)AsS(3))(CO)(11)], confirms that during the synthesis one equatorial carbonyl ligand is substituted by a monodentate arsine ligand, leaving one equatorial and two axial carbonyl substituents on an Ru atom. The other two Ru atoms each carry two equatorial and two axial carbonyl ligands. The three arsine-substituted benzene rings make dihedral angles of 77.94 (13), 86.37 (13) and 73.22 (12)° with each other. Two of the methylsulfanyl groups are disordered over two positions with refined site occupancies of 0.720 (7):0.280 (7) and 0.644 (8):0.356 (8). In the crystal structure, mol-ecules are linked into infinite chains along the a axis by weak inter-molecular C-H⋯O hydrogen bonds.