Background: Tobacco consumption is associated with considerable negative impact on health. Health professionals, including future doctors, should have a leading role in combating smoking in the community. Objectives: The aims of the study were to assess the prevalence of smoking among medical students of newly established medical colleges in Riyadh city, the capital of Saudi Arabia, as well as to assess students′ attitude, practice and their knowledge on the risk factors of tobacco consumption. Methods: A cross-sectional, questionnaire-based study of students from two medical colleges in Riyadh, Saudi Arabia was carried out. The questionnaire used was anonymous, self-administered and developed mainly from Global Adult Tobacco Survey (GATS). Results: A total of 215 students participated in this study. Forty students (19%) indicated that they smoke tobacco at the time of the study. All of them were males, which raise the prevalence among male students to 24%. Tobacco smoking was practiced by males more than females (P value < 0.0001) and by senior more than junior students (< 0.0001). About 94% of the study sample indicated that smoking could cause serious illnesses. About 90% of the students indicated that they would advice their patients to quit smoking in the future and 88% thought that smoking should be banned in public areas. Forty-four students (20%) thought that smoking has some beneficial effects, mainly as a coping strategy for stress alleviation. Conclusion: Despite good knowledge about the hazards of tobacco consumption, about 25% of the medical students in this study continue to smoke. The main reported reasons should be addressed urgently by policy-makers. Special efforts should be taken to educate medical students on the effective strategies in managing stress during their study as they thought that tobacco smoking could be used as a coping strategy to face such a stress.