Background: The aim of this study was to determine the predictors of health promoting lifestyle behaviour among medical students attending seven of the medical schools in Turkey. Materials and Methods: This cross-sectional descriptive study was performed during the second semester of the first and last (sixth) years of study from March to May 2011. A questionnaire with two sections was specifically designed. The first section contained questions on demographic characteristics; the second consisted of the Health Promoting Lifestyle Profile II (HPLP) Scale. From a total of 2,309 medical students, 2,118 (response rate 91.7%) completed the questionnaire. Data were analyzed using descriptive statistics, t, Anova, Tukey test and binary logistic regression analysis. The research was approved by the Ethics Committee of Erciyes University. Results: The mean age was 20.7 +/- 2.9 years and it was found that 55.1% were men, 62.3% were in the first year. The overall prevalence of smoking was 19.1%, and for drinking alcohol was 19.4%. HPLP point averages of the first year students were 129.2 +/- 17.7, and for last year 125.5 +/- 19.0. The overall mean score for the HPLP II was 2.5 +/- 0.4. They scored highest on the spiritual growth subscale (2.9 +/- 0.5), interpersonal relations (2.8 +/- 0.5), health responsibility subscale (2.3 +/- 0.5), nutrition subscale (2.3 +/- 0.5), stress management subscale (2.3 +/- 0.4), and the lowest subscale physical activity (2.0 +/- 0.5). It is established that student's grade, educational level of parents, economic status of family, marital status, smoking and general health perception of the students resulted in a significant difference in HPLP Scale total score average and the mean score of majority of subscales. There was no statistically significant difference between the total HPLP when evaluated for gender, chronic disease, alcohol drinking status and BMI. Conclusions: Based on these results, particularly in the curriculum of medical students in order to increase positive health behaviours including physical activity, health promotion issues, and giving more space to aim at behaviour change in these matters is recommended.