The results of adult mosquito collections from 1997 through 1998 on 14 U.S. military installations located in six provinces in Korea are presented. Adult mosquitoes were collected in New Jersey light traps from 15 May to 15 October each year. This surveillance was performed in order to determine the appropriate time for insecticidal application at these Army installations. A total of 56,998 and 59,647 adults were collected in 1997 and 1998 respectively, being comprised of 46,763 (82.0%) females and 10,235 (18.0%) males in 1997, and 47,078 (78.9%) females and 12,569 (21.1 %) males in 1998. Among the total of 23 species in 6 genera, the most common species were Anopheles sinensis (45.6%), Culex tritaeniorhynchus (29.0%), Aedes vexans nipponii (12.1 %) and Culex pipiens pallens (12.0%). Anopheles sinensis increased by 2.9% and Culex tritaeniorhynchus decreased by 3.1 % between the two years. According to the weekly population density, Anopheles sinensis at the Munsan area was more abundant in August than in July, which was an unusual pattern. The trap index for 1997~1998 was 2.5~5 times higher than that of 1995~1996.