A series of studies were conducted to evaluate the effect that microstructural refining and homogenization exerts on the deformation of a heat treatable Al-Si-Mg alloy compressed at high temperature. These studies were carried out in samples that solidified and cooled down to room-temperature at different rates, and that exhibited microstructural components of various size and shape. Some samples were homogenized to evaluate the effect that such treatment exerts on intermetallic particles. Cylindrical samples were machined from different positions within the ingots to compress them at 450°C in a universal testing machine. The samples were tested in the as-cast and homogenized conditions to the same reduction in height. It was found that the as-cast samples were susceptible to the development of cracks at the lateral surface of the samples, in comparison to those ones that were treated, and that the incidence of cracking increased as the cooling rate during solidification was reduced. Analyses of the compressed samples showed that the cracks developed at the surface of the sample and grew along the path of intermetallic inclusions.