Purpose: A small number of researchers have proposed grit as a predictor of academic, nonacademic, and non-cognitive performance. However, no such studies have been conducted in the context of Saudi Arabian medical schools. The purpose of the present study is to examine the effect of grit on the academic performance of medical students in Majmaah University. Methods: Medical students of Majmaah University completed a survey in December 2019, answering questions on grit, personal characteristics, and academic performance. Results: In the sample, the average grit score was moderately high (M = 3.31, standard deviation = 0.60). Female students' grit scores (M = 3.47, SD = 0.56) were higher than those of males (M = 3.22, SD = 0.61) (p = 0.002). Of the academic performance variables, only the difference in mean grit score between those who repeated a year or more (M = 3.11, SD = 0.64) and non-repeaters (M = 3.39, SD = 0.57) reflected a statistical significance (p = 0.001). Conclusion: The students who have repeated a year and more have lower grit scores. A follow-up study is required to compare the grit scores with the participants' ultimate completion status.