This study was on the knowledge, attitude, and practice of medical waste management in medium-sized hospitals located in D Metropolitan City in Korea. This work was intended to be used as basic data for improving the level of medical waste management. The questionnaire data were analyzed by t-test, one-way ANOVA, Scheffé's test, and multiple regression methods. The Factors influencing the knowledge of medical waste management were that males had a lower knowledge level of medical waste than females (β=-0.272, P<0.01), and it was found that the more adequate medical waste containers were provided, the higher the knowledge level of medical waste management (β=0.180, P<0.05). The factors affecting the attitude were not significant, and the factors affecting the practice showed that the higher the attitude score, the higher the level of practice (β=0.465, P<0.001). It was shown that gender and sufficient provision of medical waste containers had an effect on the knowledge of medical waste management, and the attitude toward medical waste management was identified as a factor influencing the practice. Individual education and training according to the characteristics of medical workers, and periodic guidance and inspection of medical waste managers will be required to increase the attitude of medical workers toward medical waste management. We need to construct a management process that thoroughly separates medical waste from the beginning of the medical waste generation, leading to the establishment of a positive attitude toward medical waste management.