Introduction: Biological accidents are high risk events due to the probability of acquiring agents such as HIV or HB. Medical students are exposed to these events and should be followed over time. Objective: To characterize biological accidents in medical students of a private university in Bucaramanga during the first semester of 2011. Materials and methods: Cross-sectional study with a survey applied to all student population. Univariate and bivariate analysis was done comparing age, sex, academic level, biosafety training and vaccination, with suffering a biological accident during the first semester of 2011. Results: In this population the prevalence of biological accidents was 6.8%, which means 3.42 events for every thousand weeks per student. Of the 23 events found, 9 (39.1%) were prick, 7 (30.4%) non-intact skin splash, 5 (21.7%) mucosal splash, and two (8.7%) cutting. 277 (66.4%) respondents have full hepatitis B vaccination schedule, and 33.6% have at least one dose. Only 251 (59.9%) responders have some degree of training in biosafety. No association between age, sex or academic level was found in the bivariate analysis. However, 5 students from basic levels and 5 from medical practice levels suffered more than one event in the academic period, situation that didn't happened on the surgical levels students. Conclusion: Biological accidents prevalence has decreased. However, basic academic levels have a high prevalence and recidivism, which requires new intervention strategies to further decrease the risk.