Wave interaction with a porous cylindrical breakwater is studied analytically by linear potential wave theory. The breakwater is assumed to have a thin skin, is bottom-mounted and surface-piercing. The porosity of the breakwater is uniform vertically but varies in the circumferencial direction. This allows the choice of a partially impermeable wall or a vertical slot in the breakwater. Three different basic configurations of the breakwater are investigated, namely, (1) uniformly porous cylinder; (2) porous cylinder with partial impermeable wall; and (3) porous cylinder with an opening. The performance of these types of breakwaters is studied vs. wave parameters and breakwater configurations including angle and position of opening or partial impermeable wall as well as porosity. Parametric studies with regard to the wave-amplification factor, wave forces, and elevation contours are made. The results should be found useful in the design of coastal and offshore structures.