Objective: To identify risk factors for the development of colonization by resistant microorganisms (MR) and for infections related to health care (IRCS) in patients from the emergency room (SE) of a unit of Urgent Care (PA) in a hospital university. Methods: An epidemiological study of quantitative approach, conducted between August 2009 and March 2010, among adult patients of a SE in a PA unit of a university hospital in the city of Belo Horizonte, Minas Gerais. 254 patients were followed. Results: Of 254 total patients, 6.3% were colonized with MR and 11.4% developed IRCS. We identified the time spent in the SE > 9 days (OR = 28.7) and the presence of community infection (OR = 5) for colonization by MR and, for IRCS only the time spent in the SE > 5 days (OR: 19.8), as risk factors, which is common to both the colonization of the patient for MR and to IRCS. Conclusion: This study confirmed the inadequacy of the SE, whose priority should be the qualified primary attention, resolving and/or referring patients to a specialty unit.