Microstructure and texture evolutions during tensile and compression deformation of an as-extruded Mg-11Gd-4.5Y-1Nd-1.5Zn-0.5Zr (wt%) alloy have been investigated using in-situ synchrotron radiation diffraction and subsequent microscopy. The alloy consists of 〈101-0〉 fiber texture, {1120}[0001] and {1120}〈1010〉 texture components prior to deformation. The texture evolves from [0001] to 〈1010〉 in tension, but from 〈101-0〉 to [0001] in compression. The evolution of texture is attributed to the activity of the tensile twinning and non-basal 〈a〉 type slip. The tendency of texture evolution depends on the favorable texture component for the activation of above deformation modes. The grain refinement, Mg₅(Gd, Y, Nd) and LPSO phases, and the texture contribute to the improvement in strength.