Because of the possibility of transmitting communicable diseases, in particular the HIV virus, it has been recommended that all diagnostic contact lenses, including rigid lenses, be disinfected after each use. Hydrogen peroxide is a recommended disinfection agent, but its effect on rigid lens polymers is relatively unknown. We soaked 50 lenses of 5 different polymers in 3% hydrogen peroxide for 10 min and measured the base curves to determine if any changes occurred. Our results showed no statistically significant change in base curve for the lenses measured, but 22% of the lenses did exhibit a small amount of warpage (mean 0.0382 mm) of the base curve. We were not able to determine what caused these lenses, and not all the lenses, to warp. Under the conditions of this study, hydrogen peroxide does not appear to cause clinically significant parameter changes, but lenses should be checked for warpage before use.