The larvae of 19 spp. were collected along an extreme environmental gradient from 50-2560 m altitude in central Nepal’s Gandaki River from 1984 to 1986. The number of spp. declined with increasing elevation; 12 spp. were captured in the subtropical lowlands, 10 in the mid-altitude hills, 4 in the Himalaya Mountain zone, and 3 in the high altitude trans-Himalaya ecoregion. The gomphids Davidius sp. and Anisogomphus occipitalis were most common, comprising 67% of 995 specimens, and had the widest range, occurring from 100-1189 m. The zygopteran Megalestes major and 2 anisopterans Neallogaster hermionae and Sympetrum commixtum, were collected at highest altitude; these spp. occurred in no other samples. Cluster analysis of species composition shows similarity among other high altitude collections, as well as among lowland sites, but low similarity between high and low altitude locations.