Abstract: A method for manufacturing impellers is described. The method provides for manufacturing a plurality of tubular components, each tubular component forming an inner passage, which is shaped as one of the flow passages of the final impeller. The tubular components are assembled together forming a semi-finished impeller. The semi-finished impeller is provided with annular cavities extending around the rotation axis of the impeller and gaps between adjacent tubular components. The gaps and cavities are filled with metal powder and the semi-finished impeller is subject to hot isostatic pressing, to densify the metal powder and form a monolithic final impeller.