This paper aimed to examine the determinants affecting students’ Grade Point Average (GPA) at the colleges of science in Prince Sattam Bin Abdul-Aziz University (PSAU). The study applied two approaches of Ordinary Least Square Method (OLS) and Quantile Regression (QR) to investigate the relationship between GPA and different factors; including secondary school rate, achievement test, gender, and department. The data were collected from the Deanship of Admissions and Registration for the academic year (2018) at PSAU. The sample size included (175) students selected from four departments. The data were analyzed using SAS and SPSS programs. The important results are: secondary school rate, achievement test, and gender were revealed to be variables that significantly impact GPA at all quantile levels. At 0.95 quantile the variable department has a significant effect on GPA. The OLS method revealed the significant effect of all four variables secondary school rate, achievement test, department, and gender on GPA. The study recommended that policy makers in higher education should think to add a new criterion for admission according to the privacy of every college or university.