Purpose: This study was to examine whether medical students academic motivation, general academic stress influence their perceived academic performance. Methods: Of the 606 medical students surveyed from two universities in Seoul and Incheon, 308 completed and returned the questionnaires yielding a total response rate of 50.8%. The final sample consisted of 129 premedical students (41.9%) and 179 medical students (58.1%). Of these, 189 were male (61.4%), 94 were female (30.5%), and 25 did not identify their gender (8.1%). Their average age was 22.43 years. Measures of students academic motivation, general academic stress, medical stress, and their perceptions of academic performance were obtained. Results: Pearson s correlations indicated that students perceptions of academic performance were associated with academic motivation, general academic stress, and medical stress. It was observed that there were gender differences in ‘perceptions of academic performance,’ ‘intrinsic academic motivation,’ and ‘extrinsic academic motivation.’ Females scored themselves higher in ‘perceptions of academic performance,’ and ‘intrinsic academic motivation,’ but lower in ‘extrinsic academic motivation’ than did the males. Moreover, premedical students had higher ‘perceptions of academic performance’ and ‘extrinsic academic motivation’ scores, but lower ‘general academic stress’ and ‘medical stress’ scores than medical students. Hierarchical multiple regression analyses showed that the ‘amotivation’ subscale from the academic motivation measure and ‘social-psychological’ subscale from the general academic stress measure predicted the perceptions of academic performances of the medical students after controlling for gender and education level. Conclusion: Medical educators need to be aware that medical students perceived stress and their academic motivation affects their academic performance which can have a tremendous impact on their quality of life and psychological well-being. Perhaps an academic adjustment program needs to be developed to reduce students perceived stress in medical training.