Aptitude tests should predict student success at the university level. This study examined the predictive validity of the General Aptitude Test (GAT) in Saudi Arabia. Data for 27420 students enrolled at Prince Sattam bin Abdulaziz University were analyzed. Of these students, 17565 were male students, and 9855 were female students. Multiple regression, logistic regression, and correlation analyses were conducted. The results show that the best predictor of student success at the university was the combination of high school GPA (HSGPA) and the National Achievement Test (NAT), as measured by cumulative GPA or by new students' GPA. However, the GAT was the best predictor of graduation as a criterion of success. Conclusions and recommendations for future studies are provided.