Detailed microstructural studies have been carried out on porous beta-wollastonite (CaSiO3) ceramics with 40-60% of the theoretical density. Xonotlite (Ca6Si6O17(OH)(2)) was used as starting material, and the reaction and sintering behaviour were systematically examined in the range 800-1200 degrees C in air. Analysis of the mechanical properties showed that the strength degradation of beta-wollastonite ceramics was certainly induced by the change of microstructure. Isothermal annealing at 1100 degrees C, however, did not preferentially affect the microstructure or the mechanical properties of sintered beta-wollastonite. These observations lead to the conclusion that the measured bending strength and Vickers hardness of porous beta-wollastonite ceramics can be substantially modified and improved by controlling the microstructure, in particular due to the shape of randomly oriented grains in the matrix.