Introduction: several studies in Sub- Saharan Africa have documented high and increasing premarital sexual activities among adolescents. Younger people face social, peer and cultural pressure to engage in premarital sex. As a result, significant numbers of adolescents are involved in sexual activities at an early age, which exposes them to the risk of unintended pregnancy, early marriage, abortion and STIs/HIV/AIDS. This study was conducted to determine Prevalence of premarital sexual practice and associated factors among Health science students of Mada Walabu University, Ethiopia.

Methods: a descriptive cross sectional survey was employed and three hundred twenty four students were randomly selected after proportional allocation according to their level of education. Data were collected by a self –administered questionnaire and analyzed using SPSS Version 16. Stepwise logistic regression with forward method was used to identify independent predictors of premarital sexual practices at 95% CI and P value of 0.05.

Results: of respondents 181 (59.9%) who had a boy or girl friends; about 129 (42.7%) have had premarital sexual intercourse. Out of sexually active respondents, 85 (66.4%) had one sexual partner, 44 (33.6%) had two or more sexual partners. The average age of starting sexual intercourses was 18.4 ±2.14years. Sixty three (20.9%) of respondents reported tobacco smoking and 117 (38.7%) reported consumption of alcohol consumption.

Conclusion: alcohol use, boarding, sex, educational level and discussion about sexuality were significantly associated with premarital sexual intercourses. So ,there is the need to step up Reproductive health club at the university to bring behavior change among the students in order to detain the usual consequences of premarital sexual practices and risky sexual behavior.