Flies were collected using putrefied baits once a week, a total of 31, times in Mt Jiryong, Korea from June 1, 1988 to May 31, 1989. The number of flies collected was 13,365, with sex ratio (male/female$ imes$100) fo 38.5 and the fauna of the fly was to 44 species. In the comparision of the individuals of each family collected, Calliphoridae occupied 64% of the total catch, Muscidae 31%, and Sarcophagidae 5%. In the comparision by traps of the numbers of species and individuals collected, 6,729 individuals in 25 species were collected at Trap 1, and 6,636 individuals in 28 species, at Trap 2. The five predominatn spacies, Calliphora lata, Chrysomyia pinguis, Hydrotaea dentipes, Ophyra leucostoma and Muscina angustifrons, consistuted 78.7% of the total collection. In the seasonal prevalence of the total flies from the beginning of March to the end of November, the primary peak of the male appeared in May, and that of the female in April; the secondary peak of the male appeared in September, and that of female in October; and the tertiary peaks of both sexes appeared in July. In seasonal prevalence, the female flies collected significantly outnumbered the male flies, and the numbers of species and individuals were very closely correlated. Although the number of the female flies was somewhat greater than that of the male, the patterns of seasonal prevalence were very similar at Trap 1 and Trap 2 from June to November. The number of the female collected was greater at Trap 1 than at Trap 2 in April, which is the primary peak of overall seasonal prevalence. The characteristics of five predominant species in the collection were summarized, and their seasonal prevalence and monthly change in the composition of flies collected at each trap were also compared.