Mountain pine beetle emergence was studied at 8760 ft, 9200 ft, and 9900 ft near Fraser, CO. Beetles began emerging at 8760 ft between July 9 and July 14 while no beetles emerged at 9200 ft and only one beetle emerged at 9900 ft during the same period. Beetle emergence continued at relatively low but fluctuating rates for the next two to three weeks. Peak emergence occurred about August 5 at 8760 ft, about August 12 at 9200 ft, and from August 12 to 19 at 9900 ft. Beetle emergence was complete by September 3. Average numbers of beetles emerging ranged from 5 to 256/ft2 of bark per tree with the means for each elevation not significantly different. Attack densities averaged between 6 and 9/ft2 of bark for the three elevations. Population trend ratios were computed for each tree and ranged from 0.4 to 32.0. Trend ratios varied substantially among trees but were not significantly different among elevations due to the significant variation among trees. The emergence period and population trend ratios are discussed in relation to suppression/survey projects and a stand susceptibility system.