Purpose: This study examined the relationship between the achievement of premedical students and admission characteristics at University of Ulsan College of Medicine: high school types and majors, gender, admission assessment method and interval from the high school graduation to the entrance of premedical school. Methods: Admission characteristics and demographic informations was obtained for students who entered from 1999 to 2001. Academic achievement was measured according to the results of grade point average (GPA) of total subjects and science subjects and each subject s grades. Admission characteristics and the GPA s and grades were analysed. Multiple linear regression was used to examine the relationship between admission variables and academic achievement. Results: 1. For the first year of premedical school students who studied natural science at ordinary high school, or who graduated science high school showed better achievement than others. 2. Students entered by general selection method also got significantly higher GPA s than other students in the first year. 3. Female students got significantly higher GPA s than male students in two consecutive semesters (1-2 and 2-1). 4. Students qualified by the national highschool graduation examination showed significantly lower achievement than other students in the first semester of the second year. 5. There were no relationships between achievement and other characteristics. Conclusion: Students who have academic difficulties in the first year of the premedical course is those who were not exposed to the natural science subjects. It seemed that the premedical course worked as a buffer absorbing differences from the students of various academic backgrounds in their high school period. For the second year, high school majors did not influence the academic achievement.