Background: Emotional Intelligence (EI) is the ability to deal with your own and others emotions. Medical students are inducted into medical schools on the basis of their academic achievement. Professionally, however, their success rate is variable and may depend on their interpersonal relationships. EI is thought to be significant in achieving good interpersonal relationships and success in life and career. Therefore, it is important to measure EI and understand its correlates in an undergraduate medical student population. Aim: The objective of study was to investigate the relationship between the EI of medical students and their academic achievement (based on cumulative grade point average [CGPA]), age, gender and year of study. Methods: A cross-sectional survey design was used. The SSREIS and demographic survey were administered in the three medical schools in Saudi Arabia from April to May 2012. Results: The response rate was 30%. For the Optimism subscale, the mean score was M = 3.79, SD ± 0.54 (α = 0.82), for Awareness-of-emotion subscale M = 3.94, SD ± 0.57 (α = 0.72) and for Use-of-emotion subscale M = 3.92, SD ± 0.54 (α = 0.63). Multiple regression showed a significant positive correlation between CGPA and the EI of medical students (r = 0.246, p = 0.000) on the Optimism subscale. No correlation was seen between CGPA and Awareness of Emotions and Use of Emotions subscales. No relationship was seen for the other independent variables. Conclusion: The current study demonstrates that CGPA is the only significant predictor, indicating that Optimism tends to be higher for students with a higher CPGA. None of the other independent variables (age, year of study, gender) showed a significant relationship.