Summary: The phase equilibrium diagrams of CaMgSi₂O₆-CaTiAl₂O₆ with 10, 20, and 30 wt % Ca₂MgSi₂O₇ in the join CaMgSi₂O₆-Ca₂MgSi₂O₇-CaTiAl₂O₆ were determined. Six three-phase assemblages, six four-phase assemblages, and two five-phase assemblages (isobaric trivariant, divariant, and univariant) were confirmed. The univariant assemblages are diopside_ss+forsterite+åkermanite_ss + perovskite + liquid and diopside_ss+åkermanite_ss+perovskite+spinel + liquid. Because of the complex solid solutions of diopside and åkermanite the crystallization ceases before invariant assemblages are reached and the final phase assemblage in the diopside-rich region is diopside_ss+åkermanite_ss+perovskite, in the diopside-poor region diopside_ss+åkermanite_ss+perovskite + spinel. Two invariant points, diopside_ss+forsterite+åkermanite_ss+perovskite+spinel+liquid and diopside_ss+åkermanite_ss+anorthite+perovskite+spinel+liquid in the silica-poor region of the system CaO-MgO-Al₂O₃-TiO₂-SiO₂ are estimated. The diopside solid solution in this join is discussed with its bearing on the natural titanpyroxenes from alkalic rocks including melilite.