The use of low oxygen atmospheres to control insect pests in museums looks extremely promising. It was possible to maintain low oxygen atmospheres (less than0. 1%) for at least 8-10 days with only an occasional flushing of prepurified nitrogen and several packets of Ageless® oxygen scavenger. The results showed that the time required to kill 100% of the insects varied among species and even among the developmental stages of a given species. For most insects tested, exposures of less than 72 hours were required to insure complete kill. Certain stages, such as eggs of cigarette beetles, may require up to eight-day exposures to insure complete kill. Preliminary tests indicated that the addition of carbon dioxide to the nitrogen slightly decreased the exposure time required to kill the insects. However, if increased temperatures or decreased relative humidities could be tolerated by the objects, they would probably have a much greater effect than using carbon dioxide and nitrogen mixtures in reducing exposure times. The time required to kill the most resistant stages of each insect tested did not significantly increase in Stage III testing. The oxygen was quickly displaced and removed by the Ageless®, killing the insects buried deep in the wood or flour. Consequently, it would probably not be necessary to specially prepare or stack items for treatment. The future use of controlled atmospheres to control museum pests largely depends on the development of chambers or bags large enough to hold furniture, paintings, and other objects. Special bags capable of enclosing larger items and still maintaining the low oxygen atmosphere are needed. If such bags and chambers could be developed, the use of low oxygen atmospheres will replace the current use of insecticide sprays and fumigants.