Background: Consumption of energy drink represents an escalating global public health problem especially among adolescents and young adults. Energy drink contains stimulants mainly caffeine that marketed as mental and physical stimulator although there are many safety concerns against use. Objectives: To determine the prevalence, pattern and predictors of energy drink consumption among medical students and interns in medical colleges, Jeddah, Saudi Arabia. Materials and methods: A cross-sectional study was conducted at three medical colleges (the governmental medical college of King Abdulaziz University and other two private colleges). A multistage stratified random sample technique was used with selection of 610 medical students & interns. Data was collected using a validated, confidential & self-administered questionnaire. SPSS version 21 was used for statistical analysis. Results: More than one-half of the participants (52.6%) had "ever" tried energy drinks, while 33.4% consumed it regularly during the two months preceded the study. Friends, advertisement and curiosity were the inspirations for starting. Among regular users, the commonest reasons for consumption were enjoying leisure time with friends (57.5%), boosting energy for studying (56.4%), and staying awake for long hours (50.5%). However, 31.6% of regular energy drinks consumers experienced adverse effects as palpitation, insomnia and frequent micturition. In bivariate analysis, regular consumption of energy-drink was significantly associated with male gender, students from private colleges and smokers. After controlling of confounding factors smoking was the only predictor of energy drinks consumption (aOR= 3.68; 95% CI: 2.36-5.71). Conclusion: Consumption of energy drinks is rather common among medical students and interns despite of high prevalence of adverse effects. Smoking is the most important predictor. Implementation of educational awareness campaigns, especially in medical colleges, about healthy dietary habits, potential benefits, side effects and correction of wrong perceptions about energy drinks is urgently needed. Policies for energy drinks consumption and smoking control programs are also recommended.