Study on distribution, behaviors and transmission indexes of malaria vectors in provinces of Gia Lai, Dak Lak, Phu Yen and Quang Nam was conducted during 2011-2012. A total of 24 Anopheles species were collected in the study sites, including Quang Nam (15 species), Phu Yen (19), Gia Lai (16), and Dak Lak (16). The primary vectors found in the study sites are A. Dirus and A. minimus, and secondary vectors are A. aconitus, A. jeyporiensis as well as A. maculatus. In this study, the authors identified the A. dirus species (A. dirus A) belonging to the A. dirus group in Dak Lak, Phu Yen and Gia Lai. For An. minim us group, the authors found A. minimus A in Quang Nam, Gia Lai, and Dak Lak provinces
and A. harrisoni (An. minimus C) in Phu Yen province. A. dirus was collected by cattle shelters method at a much lower raie (21 percent) than by human bait method (79 percent). The remaining primary vector (A. minimus) and secondary vector were collected at higher rates by shelter catches than human bait. A. dirus showed a higher density of outdoor biting (0.19 mosquyto/hour/person) than indoor biting (0.13 m/h/p). A. dirus was found biting humans at the highest density (0.31 m/h/p) in Phu Yen, whereas in the highest density of A. minim us biting humans was in Quang Nam (0.12 m/h/p). In Quang Nam, almost mosquytoes of the A. minimus group were caught by indoor human bait method (20 percent), outdoor catch (8 percent), indoor light-trap catch at highest rate (48 percent), and light trap catch in cattle shelters (24 percent). In Phu Yen, A. harrisoni was collected by indoor light-trap catch (6.1 percent) and in cattle shelters (93.9 percent).