Phase equilibria in the Nd1-xNaxMnO3, Nd1-xKxMnO3, and Nd1-xAgxMnO3 systems (0.0less than or equal toxless than or equal to1.0) and the crystal structure of the phases of variable composition formed in these systems in air at 1100 C were studied. The formation of Nd1-xMxMnO3 (M=Na, K) solid solutions with an orthorhombic structure was observed in the composition range 0less than or equal toxless than or equal to0.15. An increase in x caused the phase transition from the orthorhombic to the rhombohedral structure: Nd1-xNaxMnO3 and Nd1-xKxMnO3 formed stable rhombohedral phases in the composition ranges 0.15less than or equal toxless than or equal to0.45 and 0.15less than or equal toxless than or equal to0.25, respectively. In the Nd1-xAgxMnO3 system, orthorhombic solid solutions were only formed in the narrow composition range 0.0less than or equal toxless than or equal to0.10.