Crystal structures and magnetic properties of Ba3MRuIrO9 (M = lanthanides, Y) were investigated. Rietveld refinements using powder diffraction data indicate that all the compounds crystallize in the 6H-BaTiO3 structure type in space group P6(3)/mmc. Magnetic susceptibility measurements were carried out on each compound. Effective magnetic moments were smaller than values estimated using spin-only moments, which indicate the presence of spin-orbit coupling and strong interactions in the [(Ru0.5Ir0.5)(2)O-9] face-sharing octahedra that contain a disordered mixture of Ru and Ir on a single crystallographic site. Magnetic anomalies were observed for the compounds Ba3PrRuIrO9, Ba3TbRuIrO9, and Ba3NdRuIrO9 at 3.5, 13, and 8 K, respectively.