Five silos of No 2. yellow shelled corn at a temperature of 72-77° were used in an evaluation of phosphine gas as a fumigant. The phosphine was released from aluminim phosphide applied in tablet from. One bin was left as an untreated control and the other four were treated at 2, 3, 4 and 6 tablets per ton. Test insects, adult confused flour beetles and immature rice weevils were exposed in the fumigated grain for seven days. The amount of phosphine gas was determined at 24, 48, 72 and 96 hours from the surface, bottom and 20-foot, 40-foot, 60-foot and 80-foot depths. A 100per thousand mortality of both confused flour beetle adults and the immature rice weevils was obtained at each dosage rate used. The gas analysis tests showed the phosphine gas to be distributed to all sampling points in the grain mass.