Throughout Korea, small mammals are hosts to a number of disease-causing agents that pose a health threat to U.S. and Korean military forces while they conduct field-training exercises. A seasonal rodent-borne disease surveillance program was established at two firing points (FP), FP-10, and FP-60, and conducted over five years from 2001 through 2005 in response to hantavirus cases among U.S. soldiers. The ecology of these sites consisted primarily of tall grasses associated with semi-permanent and temporary water sources (drainage ditches and a small stream) and dry-land agriculture farming. Eight species of rodents and one species of insectivore were collected, including Apodemus agrarius, Micromys minutus, Mus musculus, Rattus norvegicus, Tscherskia triton, Microtus fortis, Myodes regulus, and Crocidura lasiura. The striped field mouse, A. agrarius, (primary reservoir for Hantaan virus, the causative agent of Korean hemorrhagic fever), was the most frequently collected, representing 90.6% of the 1,288 small mammals captured at both sites. Reported herein are the ecological parameters, seasonal population densities, and seasonal population characteristics associated with small mammals collected at two military training sites in the Republic of Korea.