A breast prosthesis comprises a resiliently-compliant silicone shell (1;11) which has an outer wall (2;12) configured to simulate the shape of a female breast. The wall (2;12) is fretted with an ornamental pattern of perforations (6;16) that vent the internal cavity (4;14) of the shell (1;11), and ribs (5;15) within the cavity (4;14) extend across it in resiliently supporting and retaining the breast-shape of the shell (1;11). The ribs (5;15) are interconnected with one another and are molded integrally with the outer wall (2;12). The shell (1:11) has a flat peripheral rim (3:13) to the cavity (4:14).