Background: The pre-internship (PI) exam is the most important examination of medical students which can assess their abilities in passing the general medicine.Objective: To determine the effective factors on the pre-internship score and result at Zahedan University of Medical Sciences.Methods: The research was a cross-sectional on 63 medical students participating in preinternship examinations in Zahedan University of Medical Sciences in 2000. The mean scores of basic sciences, physiopathology, clinical, total and the scores of ten important courses of preinternship exam and the demographic variables were recorded and analyzed.Results: The failing rate was 20.4%, the relative risks of failing were 3.6, 3.7, 6.1, 10.9 and 11.6 for the students with non-district group in quota system, high age, more than 5.5 year education period (to pre-internship), with clinical score mean and total mean lower than the mean of all participants, respectively and it was significant. Also, the mean of pre-internship scores was significantly different based on marital status, situation in quota system, age, education period. A high correlation was observed between pre-internship score and total scores mean, physiopathology, basic sciences and clinical scores, respectively (0.79, 0.75, 0.73 and 0.73).Conclusion: Age, quota system, education period, the clinical score mean, infectious diseases, pharmacology and psychiatry scores are the most important factors influencing the exams results, due to high and significant relative risks. Marital status, quota system, age and education period cause the students taking part in a preinternship exam to get different means.