Purpose: This study evaluated the dynamic mechanical properties of silicone elastomers for maxillofacial applications and the influence of frequency and temperature on their properties. Materials and Methods: Seven currently used silicone maxillofacial prosthetic materials were used. Storage modulus, loss modulus, and loss tangent were determined over the frequency range from 0.01 to 100 Hz at both 23 and 37°C using a dynamic viscoelastometer. Contribution ratios of type of material, temperature, and frequency for each rheologic parameter were also determined. Results: Storage modulus, loss modulus, and loss tangent of all materials were greater at higher frequencies. Loss tangent and loss modulus were especially affected; the contribution ratios of frequency were 72% and 48%, respectively. These three rheologic parameters were insensitive to changes in temperature over the range tested; contribution ratios of temperature were less than 3%. There were significant differences in dynamic mechanical properties among the materials. Elasto Synsil showed higher storage modulus and loss modulus than the other materials (Cosmesil T001, Elastosil M3500, Episil, Ideal, Premium, Silskin 2000) at all frequencies and temperatures tested. Loss tangent values ranged from 0.02 to 0.20. Silicone maxillofacial prosthetic materials had almost no viscous component and exhibited elastic behavior. However, a wide range of ability in energy absorption was found among the materials. Conclusion: The results suggest that a maxillofacial prosthesis should have a laminate or hybrid structure consisting of both the material with a greater cushioning effect and that with a higher elastic recovery. Int J Prosthodont 2003;16:369–374.