The present work was carried out in the frame of a scientific cooperation between the Trento University and MIMEST spa (Italy), a company specialized in the production of parts by metal injection molding (MIM) of powders The cooperation was established to develop the applications of MIM products in the biomedical fields, with the production of both prosthesis and external tutors and surgery tools. The work has been carried out on cobalt alloys, titanium alloys, austenitic stainless steel and precipitation hardened stainless steels. The main focus of this research was properties optimization of these materials, there were several open points concerning the effect of the as sintered microstructure on some of the properties which are requested for the specific applications. The common approach was the study of the microstructural characteristics which are decisive in determining the properties, the possibility to modify them by either heat treatment or mechanical treatment, and the correlation with the specific properties. Only the work on cobalt and titanium alloys are described in detail. However, the work done on stainless steel is reported in two papers in the appendix.