A shoulder prosthesis includes a humeral portion and a scapular portion, each having an osseointegrable component and an articular component. The osseointegrable component in the humeral portion includes a humeral body produced as a semicircular asymmetrical cage having a proximal circular ring base facing the scapular portion and an eccentric distal cylindrical base in opposite position, which are connected by arms having one or more holes for favoring the growth of bone tissue and facilitating anchorage to the bone, the proximal circular ring base being configured to be interchangeably coupled with the articular component for an anatomical prosthesis or a concave insert for a reverse prosthesis. The osseointegrable component in the scapular portion includes a glenoid base-plate of asymmetric form for coupling to an articular component, such as a concave glenoid insert, for an anatomical prosthesis or a glenosphere for a reverse prosthesis.