Semi-Solid metal (SSM) processing has been introduced as a rather new near net shape manufacturing method duo to its unique advantages relative to the conventional metal forming processes (casting and forging). Semi-solid processing is typically In this study a cup-shaped SSR processed casting made from A356 alloy was produced in a squeeze casting die and its microstructural characteristics and mechanical properties were studied. After some preliminary experiments to determine the SSR process parameters, the effects of pouring temperature (solid fraction) and applied pressure on the surface quality, casting density, microstructure, internal and external volumetric defects and mechanical properties of the produced components were investigated. Six pouring temperatures of 645 and 700 ° C (in the liquid state) and 595, 590, 585, and 580 ° C (in the semi-solid state) under 10 MPa external pressure and four external pressures of about 10, 30, 50, and 70 MPa at pouring temperature of 590 ° C were employed. Results showed that the surface quality of the castings produced in semi-solid state was rather poor relative to the castings poured from the liquid state. Moreover, with decreasing the pouring temperature (increasing the solid fraction) in semi-solid state, the surface quality of the castings was deteriorated. This problem was diminished with applying a thicker die coating. Densities of the components produced in semi-solid state were more than the components formed in the liquid state and densities of components were increased with increasing the applied pressure. Results indicated that with increase in the solid fraction, roundness and average grain size of primary solid particles increased. It was observed that the solid fraction of the primary particles at the bottom of the castings was more than other points due to the liquid segregation. This phenomenon was studied in various solid fractions and a model was suggested to explain the occurrence of liquid segregation during squeeze casting process. The shrinkage defects observed in fully liquid cast components were eliminated in SSR cast ones. Furthermore, the results showed that the mechanical properties of the castings were influenced by liquid segregation. In conclusion, low solid fraction slurries appeared more suitable for squeeze casting than high solid fraction slurries because of the better surface quality, less liquid segregation and better mechanical properties of the castings. Key words : SSM, SSR, pouring temperature, applied pressure, liquid segregation, A356.