Friction stir processing (FSP) was used to fabricate Al/Cu metal matrix composite (MMC). The effects of two different tool pin profiles (straight cylindrical and square) and the number of FSP passes on microstructure, tensile properties and microhardness were studied. The results indicated that good dispersion of micro-sized Cu particles, finer grains, higher tensile properties and higher microhardness, can be achieved by the square tool pin profile compared to the samples produced by the other tool. Also it was observed that the ultimate tensile strength of the samples produced by two FSP passes, as a result of Cu particles shattering, increased intensively compared to the samples fabricated with first FSP pass. Further FSP passes increased the elongation of the composites without any considerable changes in yield and ultimate tensile strength.