Interpenetrating polymer networks (IPNs) of polydimethylsiloxane (PDMS) and poly(2-hydroxyethyl methacrylate) (PHEMA) were prepared by sequential method. The dynamic mechanical parameters of obtained IPNs and their variations with the structural composition were evaluated. The results for the IPNs were compared with corresponding physically blended systems. The tensile properties and damping factor (tan delta) were assessed by stress-strain measurement and dynamic mechanical thermal analysis (DMTA), respectively. The glass-rubber transition temperature (T-g) was assessed by DMTA and differential scanning calorimetry (DSC). The results showed higher tensile strength and elongation at break for IPNs than those for physical blends. The shifts of T-g for that two components that make up the IPNs were greater than those for corresponding blends.