Hot tearing is a common defect encountered in large freezing range cast alloys. It occurs when the linear contraction of the alloy which is going through its semi-solid state is hindered by rigid cores or mold sections. It has been shown that hot tearing includes two distinct stages of nucleation and growth, and that volumetric defects such as gas and shrinkage porosity as well as entrained inclusions facilitates nucleation of hot tears. For this reason, cast metal matrix composites are expected to have higher susceptibility to hot tearing than their monolithic counterparts. In the present research, the occurrence of hot tearing in Al-4.7%Cu-SiC P cast composites and their monolithic alloy was studied by computer simulation using PROCAST software as well as by real casting experiments using Instrumented Constrained T-shaped Casing (ICTC) method. Also the effects of magnesium addition to the melt and use of feeding system were investigated. To study the influence of reinforcing particles on the occurrence of hot tears, changes in contraction force developed during solidification of the castings was measured. The simulation results indicated that the intensity of hot tearing decreases by incorporation of the feeding system and increases by addition of the reinforcement particles. The maximum contraction force measured in the experimental work for the monolithic and the reinforced samples, both cast using the feeding system, was 7380 N and 5420 N, respectively. This confirms that the reinforcement addition increases the hot tearing intensity. Use of feeding system, however, did not show any logical relationship with hot tearing. The maximum contraction force measured for the reinforced samples cast without feeding system with and without 2% Mg addition was 7750 N and 9330 N, respectively. This shows that 2% Mg addition has reduced the hot tears tendency. Keywords: Hot tear, Metal matrix composite, ICTC test, Al-4.7%wt.Cu, Al-Cu-SiC.