Dry sliding wear of Al-Si cast alloys with three different compositions and different microstructures have been examined. A pin-on-disk machine was used for this purpose with silicon carbide paper counterface. Worn surfaces and microstructures of Al-Si alloys were examined by scanning electron microscopy and optical microscopy, respectively. Optical microscopy examinations revealed that the microstructures of these alloys were altered by heat treatments and with Na additions. The results show that the microhardness and the wear resistance increase as the silicon content increases. Spheroidising heat-treatment and Na-modification are observed to enhance the hardness and the wear resistance of these alloys.