One method of hardening optical glasses against radiation-induced darkening has been to add CeO(2) to the batch composition. In the present investigation we prepared a series of lanthanum crown glasses with varying degrees of CeO(2) additions and melted them at 1,400 °C with and without bubbling oxygen gas. We examined the influence of added oxygen on the optical transmissions of these glasses in the spectral range 460 to 760 nm following gamma irradiations ranging from 10 to 250 krad. The results showed that dose-for-dose the radiation-induced optical attenuations of the oxidized glasses were greater than for the glasses without added O(2).