Preventive medicine has been incorporated in the medical school curriculum, but its effectiveness and the factors that affect it are yet to be widely looked into in the context of Malaysia. We aimed to measure the familiarity with, perception about the importance to learn, and the ability to practice preventive medicine as well as its determinants among the medical students in Malaysia. Thus, a cross sectional study was conducted through an anonymous online survey among 387 randomly selected final year medical students of four large public medical schools in Malaysia from March to September 2014. Of the total sample, 340 (response rate 87.8%) gave a written informed consent and took part in the survey. The familiarity of the sample with preventive medicine was measured in 19 preventive medicine areas, and their perception about the importance of preventive medicine and their ability to practice it were gauged on a Likert scale (low score indicates disagreement and high indicates agreement). Descriptive statistical analysis was performed, followed by logistic regression. The mean age of the respondents was 23.7 (SD 0.77) years, and 61.2% (n = 208) of them were females. Results showed that 22.9% of the sample (n = 78) had a low familiarity with preventive medicine, whereas 76.8% (n = 261) had a high familiarity. The study sample specified that among all the preventive medicine subjects, screening and control as well as smoking cessation and immunization are "extremely important to learn." In univariable analysis, being a female, medical school, family size, and perception about the importance to learn preventive medicine were associated with the ability to practice it. In multivariable analysis, the perception towards the importance to learn preventive medicine was the only significant determinant: aOR (adjusted odds ratio) for those who "agreed" 17.28 (95% CI aOR 4.44-67.26, P < 0.001) and for "strongly agreed" 35.87 (95% CI aOR 8.04-159.87, P < 0.001). Considering these findings, the familiarity of medical students with preventive medicine should be increased. The perception about the importance to learn preventive medicine is a strong determinant for the ability to practice it.