Metal Matrix Composites (MMCs) are attractive for tribological applications owing to their high hardness and strength that promote wear resistance. Composites with light metal matrices are even more attractive as they provide excellent strength-to-weight ratio. In this paper, the tribological characteristics of magnesium nanocomposites are presented. Reports on tribological research on magnesium nanocomposites are few as synthesis of magnesium nanocomposites by itself is a great challenge. Examples discussed in the paper include pure magnesium and AZ31 alloy based composites reinforced with Al2O3 nanoparticles. Operating wear/friction mechanisms and the influence of metallurgical factors (e.g. grain size, precipitates, intermetallic phase) that determine the tribological response of the nanocomposites are highlighted.