To determine the prevalence of overweight and obesity among Jordan University students and to investigate some factors that might be associated with overweight and obesity. A cross-sectional survey was conducted at Jordan University, Amman, Jordan from March to September, 2005 using a multistage stratified sampling technique to recruit the participants. A total of 1219 students aged 17-28 years completed the study procedure with a response rate of 81.3%. A self-administered questionnaire was used for data collection. The questionnaire included questions on biological and non-biological factors influencing the development of overweight and obesity. Also, height and weight were self reported to calculate the Body Mass Index (BMI) and to categorize it into normal, overweight and obese according to WHO (1997) classification. The overall prevalence rates of overweight and obesity among university students were 28.5 and 10.2%, respectively. Biological factors significantly associated with overweight and obesity were increasing age, being female and parental obesity (p<0.05). Also, non-biological factors including, physical inactivity, non-healthy diet, lower family monthly income and being non-smoker were significantly associated with overweight and obesity (p<0.05). Obesity is a problem among Jordan University students. Factors behind overweight and obesity among Jordan University students were increasing age, being female, parental obesity, physical inactivity, non-healthy diet, lower family monthly income and being non-smoker.