A number of magnesium-based alloys containing up to 20 at % Ni and 15 at % Nd were cast directly into a wedge shaped mould and also rapidly solidified by chill-block melt-spinning to produce ribbons between 30 and 100 mu m in thickness. The formation of the amorphous state in the wedge and ribbons was confirmed by X-ray diffraction and differential scanning calorimetry. The measured tensile fracture strength and microhardness of these ribbons were found to be in the range 330-630 MPa and 190-250 kg mm(-2), respectively, which are significantly higher than for conventional magnesium alloys. Critical cooling rates for the glass formation of these alloys were obtained from wedge section thickness, Bridgman growth, thermal analysis data by differential thermal analysis and computational methods. The significance of several parameters for the glass-forming ability of these alloys is discussed.