A medical device, particularly for mixing medical fluids, comprising two tubular bodies (1, 2) made of materials of different elasticity having respective open ends (7, 11) to be joined together. The end (11) of the second body (2) is inserted axially by friction within the end (7) of the first body (1) and is then blocked via radial projections (15), which are obtained by plastic deformation of the wall of the end (7) of the first body (1) and are engaged against the end (11) of the second body (2).