Background: University student populations are widely reported to engage in high rates of physical inactivity, sedentary behaviours, and unhealthy dietary habits. There is rising prevalence of overweight and obesity among university students. Aims of study: Assessment of body mass index among university students, detection of obesity and underweight prevalence among students and determining risk factors of obesity among university students. Methods: This study is a cross sectional study conducted for assessment of body mass index and obesity prevalence among university students among 714 students; (426 from Faculty of Medicine and 288 from faculty of Arts and social sciences) were included in the study, using a self-administered questionnaire which include demographic characteristic sand measuring weight and height. BMI was calculated as weight (kg) divided by the square of height (m2). A digital scale was used for the measurements. Results: weight index of studied students was within the range of normal (24.12 ± 4.76). (59.5%) of students were normal weight, (27.6%) were overweight, (8.3%) were obese and only (4.6%) were underweight. Body mass index was significantly higher in urban and fourth grade students. University resident students were 1.58 times significantly more likely to have a higher BMI ≥ 25 than non-residents. Conclusions: as there are more than 35% of students have body mass index ≥35, so that, universities should consider the establishment of on-campus exercise facilities in attainable prices to encourage students to exercise especially because they spent a substantial part of their time in the university