Background: It is known that basic science and general courses play a vital role in training of medical students. The medical students' comprehensive basic science EXAMINATION (CBSE) scores seem to be a potential tool for predicting their comprehensive pre-internship EXAMINATION (CPIE) scores. Purpose: To evaluate the predictive validity of medical students' CBSE scores for predicting their CPlE scores. Methods: We conducted a cross-sectional study on 103 medical students of Rafsanjan University of Medical Sciences registered for the first time as medical student in 1988, 1992 and 1996. We used a regression analysis to study the predictive validity of these students' CBSE mean scores for predicting their CPlE mean scores.Results: Fifty-two students were male and 51 students were female. CBSE mean scores were 121.22±15.8 for all of the students, 119.70±14.82 for the female students and 122.71±16.71 for the male students. The Pearson correlation coefficient between CBSE and CPIE mean scores was 0.598. Simple linear regression showed that CBSE mean score had 0.358 predictability for CPIE mean score; however, the results showed that correlation coefficient and predictive validity progressively decreased during the period between 1988 and 1996.Conclusion: Our results reflected the usefulness of CBSE mean score for predicting CPlE mean score. This should be confirmed in studies in other medical universities.