The effects of X-ray irradiation on mortality and sterility of the cigarette beetle, Lasioderma serricorne (F.), were studied at doses ranging from 0.05 to 0.2 kGy. Irradiation above 0.1 kGy prevented eggs and larvae from developing to the adult stage. The irradiated larvae remained at the larval or pupal stages for months without further development and ultimately died of desiccation. Irradiation did not affect the viability of pupae and adults but seriously affected their fertility. Females were completely sterilized above 0.1 kGy, although males retained weakened fertility at all doses tested. These results suggest that X-ray irradiation at 0.1 kGy can completely break the reproductive cycle of the cigarette beetle, even though the action is not immediate, and therefore it would be applicable for the disinfestation of stored tobacco.