The purpose of this study was to test the effect of treatment in a gravity steam autoclave, high-vacuum steam autoclave, or an unsaturated chemical vapor sterilizer on endospores present on strips or placed inside of dental anesthetic cartridges held within sharps containers. Strips with 1.7X10 5 Bacillus stearothermophilus endospores were used the cartridges were soiled with an equal number of spores or spores mixed with blood. If sterilization was not accomplished after the initial period, additional exposure time was added. Neither the presence of blood or anesthetic solution nor the position of the container affected the efficiency of sterilization. Soiled cartridges were much more difficult than strips to sterilize. Intact cartridges could not be sterilized by two runs in a gravity steam autoclave or an unsaturated chemical vapor sterilizer or one run in a high-vacuum steam autoclave. Sterilization occurred after two runs in the gravity steam autoclave and unsaturated chemical vapor sterilizer only when one end of the cartridge was removed prior to processing. Results indicated that unopened spore-soiled cartridges are not readily sterilized by commonplace office sterilizers, even after extended exposure.