AbstractMaxillofacial prosthetic materials are used to rehabilitate patients suffering from acquired or congenital facial disfigurement. Silicone rubber materials [poly(dimethylsiloxane) rubbers] are the materials of choice. However, current formulations have inadequate mechanical properties, in particular, tear strength. The purpose of this study was to formulate a new poly(dimethylsiloxane) material with improved mechanical properties in comparison to commercially available materials. The formulations developed were based on condensation chemistry containing a hydroxy–end‐blocked poly(dimethylsiloxane), hydrophobic silica filler, silane cross‐linking agents, and a tin catalyst. The following parameters were varied in order to formulate improved materials: (a) bimodal polymeric mix (i.e., ratio of high‐ and low‐molecular‐weight polymers); (b) silica filler type and quantity. By varying these parameters a formulation was developed with a base polymer mix of 80%:20% high‐ to low‐molecular‐weight polymers into which 20% w/w filler was added. This formulation had a tear strength of 22.23 ± 1.6 m N/mm compared to the commercial materials having tear strengths in the range 4.53–17.63 N/mm. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 65B: 252–261, 2003