High School, Aptitude and Achievement Tests have been utilized since 2002 in Saudi Arabia for the purpose of student selection to health sciences and medical colleges. However, longitudinal studies determining the predictive validity of these so-called cognitive tests for in-course performance is lacking. Our aim was to assess the predictive validity of Saudi health sciences and medical school pre-admission selection tools for in-course performance over a three year period and therefore we conducted a retrospective review of pre-admission (High School Test, Saudi Aptitude and Achievement tests) and in-course academic performance data (Grade Point Average, GPA) for all students enrolled in undergraduate Health Sciences Colleges and College of Medicine, 2007-2010. Correlation and linear regression analyses were performed for the whole cohort. Data are reported on 87 of 1,905 (4.6%) students who applied to Health Sciences and Medical Colleges. The results indicate that in-course GPA scores in year three were significantly positively correlated with High School (r = 0.65; p < 0.05), Aptitude (r = 0.65; p < 0.05) and Achievement (r = 0.66; p < 0.05) selection test scores. Furthermore, the High School Exam was the best predictor of achievement in year three. Regression analysis revealed that 54% of the variance in predicting academic performance is explained by the three test scores. Results confirmed our hypothesis that High School, Aptitude and Achievement tests are statistically predictive of academic performance in health sciences and medical colleges. Further longitudinal, national work is nevertheless required to determine the extent to which pre-admissions cognitive and non-cognitive tests, socio-demographic and educational process variables predict undergraduate and postgraduate achievement and performance.