In the title triangulo-triruthenium compound, [Ru(3)(C(21)H(21)As)(CO)(11)], one equatorial carbonyl group has been substituted by the monodentate arsine ligand, leaving one equatorial and two axial carbonyl substituents on the Ru atom. The remaining two Ru atoms each carry two equatorial and two axial terminal carbonyl ligands. The three arsine-substituted phenyl rings make dihedral angles of 73.2 (2), 71.0 (2) and 75.3 (2)° with each other. In the crystal packing, mol-ecules are stacked down the b axis and each mol-ecule is stabilized by an intra-molecular C-H⋯O hydrogen bond.