Fast food restaurants are growing in numbers in Korea since they were introduced abot a decade ago. To develop an effective marketing strategy for fast foods, it is important to assess consumer's acceptability and identify demorgraphic, environmental, and managerial factors which influence consumer's perception on the fast food restaurants. A total of 595 customers were surveyed at thirty hamburger chain restaurants in Seoul from November 7 to 15, 1988. Analyses of the collected data revealed that adolescents, females, and the people with high income were the major customers and visited more than once or twice a week; frequent visitors rated meals more favorably in terms of the quality, service and cleanliness, and they also rated meals of foreign brand more favorable than those of domestic one; the female group perceived the change in their dietary habits more than any other groups; cleanliness, convenience, atmosphere, courtesy, and the taste of foods were significant factors in purchasing fast foods; and customers were most satisfied with convenience, while least satisfied with the price and the quantity of foods. From these findings, it is sggested that the manager of the fast food restaurant must consider the consumer's perception of fast foods in terms of pros and cons in order to operate her/his restaurant successfully.