The aim of this work is to compare two different as-cast CoCrMo alloys. The microstructure of a cobalt-base alloy obtained by the investment casting process was studied. These alloys comply with the ISO 5832-4 standard and are widely used in the manufacturing of orthopedic implants because of them high strength, good corrosion resistance and excellent biocompatibility properties. This work focuses on the resulting microstructure arising from samples poured in vacuum furnace. The characterization of the samples was achieved by using optical microscopy, scanning electron microscopy (SEM) and energy dispersion spectroscopy techniques (EDS) for semi-quantitative chemical analysis. The hardness was measured by instrumented indentation test, microhardness test was applied to investigate microhardness of matrix and precipitates. General the as-cast microstructure is a Co-fcc dendritic matrix with the presence of a secondary phase, such as the M23C6 carbides precipitated at grain boundaries and interdendritic zones. These precipitates are the main strengthening mechanism in this type of alloys.