Introduction: Biological risk is most frequent among health care workers. Resident physicians are particularly susceptible due to their relative inexperience and exposure to high volume of patients and long workdays. Objectives: To determine the prevalence, characterization and associated factors of biological accidents among hospital resident physicians. Materials and methods: Cross-sectional study on resident physicians in surgical and medical services at Universidad Industrial de Santander (Bucaramanga, Colombia). Results: Of 79 resident physicians, 73 (92.4%) answered the survey. Of these, 49.3% routinely used complete protection (gloves, face mask and protective eyewear); 35 (48%) reported having sustained at least one accident in their lifetimes, and 29 (39.8%) reported at least one accident during the course of their residencies. The last accident was not reported by 31%. Factors found to be associated with a biological accident during residency were a surgical residency, which compared to a medical residency yields a PR=3.17 (CI 95% 1.27 – 7.94; p=0.014); also, having sustained a biological accident as an undergraduate medical student yields a PR=2.55 (CI 95% 1.53 – 4.27; p<0.001). Conclusions: Biological accidents are frequent among resident physicians, especially those on surgical residencies and most occur inside the operating room. Strategies aimed at reducing the number of biological accidents carried out in a systematic way and measures to make reporting easier are needed.