Introduction: In recent years the discussion about patient safety has gained space on the world scene in the face of evidence that health care damages are frequent. Considering that care should provide for risk situations to minimize possible effects of unsafe care, investigating the risk factors for the occurrence of such incidents can help in reducing negative health care outcomes. Objective: To analyze the factors associated with incidents without harm and adverse events occurred in the Surgical Clinic of a university hospital in the Center-West Region of Brazil. Method: Retrospective cross-sectional study conducted with a sample of 750 admissions occurring during the year 2010. Data were collected between January and May of 2011, using a validated instrument. The data sources consisted of the patients' records, with the health records as the focus of analysis. To identify the associated factors, chi-square and Fisher's test were used. After multivariate analysis, associations with p <0.05 were considered statistically significant. Results: It was evidenced that the hospitalization time greater than three days, the use of probe and the infusion of hemoderivatives increase the risk of adverse events. For incidents without damage, the risk factors were hospitalization time greater than three days, use of a catheter, and prescription of three or more medications per day. Conclusion: The present study of the associated factors directs clinical decision making and favors the adoption of safe measures.