Pin-on-disk dry sliding wear tests at sliding speeds ranging from 0.6 to 1.25m/s and under loads ranging from 3.98 to 6.37MPa (50–80N) were conducted for pin specimens of composites with Al-5083 matrices reinforced with 5 and 10wt.% B 4 C particles. The wear rate of the composite with 10wt.% B 4 C was approximately 40% lower than that of the composite with 5wt.% B 4 C under the same test condition. Two stages were observed in the reduction of pin length/sliding distance curves in several specimens, with the length reduction rate in the first stage being one to two orders of magnitude lower than that in the second stage. The low length reduction rate in the first stage corresponded with a flat stage with a low coefficient of friction (COF) in the COF/sliding distance curve.