The paper reports on a detailed investigation of microstructure and phase composition of rapidly solidified and annealed AlNi18.5 and AlNi17Zr1.8 ribbons. The ribbons were prepared by the melt spinning (planar flow casting) technique. The microstructure and phase composition have been studied by TEM and XRD. The specimens were annealed and subsequently subjected to microstructure investigations to asses their thermal stability. Rapidly solidified alloys are composed of a-Al and Al3Ni phase grains. No significant difference in the shape between Al and Al3Ni grains was found. The Al9Ni2 metastable phase was identified in the rapidly solidified AlNi17Zr1.8 alloy and the Al3Zr phase precipitates from the a-Al solid solution in the AlNi17Zr1.8 alloy after the high temperature annealing.