This study aimed to identify microorganisms present in contaminated dental lab coats and determine the risks of microbial contamination to professionals and patients. The study included 10 dentists of the city of Foz do Iguaçu, state of Paraná, Brazil, who signed an informed consent form according to the ethics committee on human research. Microbiological samples were collected from coats using the rolling swab technique, passing a single swab moist in BHI medium in the collar, cuffs and pockets. A questionnaire with open and closed questions was used. Statistical data were tabulated and described in a descriptive analysis through the bioestatic software 5.0. Regarding coat sanitization, 80% of respondents adopted this procedure every five days of use. Diagnosed microorganisms were: Klebsiella sp., Staphylococcus saprophyticus, Enterobacter sp., Staphylococcus epidermidis, Staphylococcus aureus. Staphylococcus aureus (50%) and Staphylococcus epidermidis (40%) were the most predominant bacteria found, especially in coats analyzed at the end of the workday, which may cause diseases such as: folliculitis, furuncle, endocarditis, meningitis, osteomyelitis, arthritis, urinary tract infections and others. Based on results, it was found that the lab coats of dentists are contaminated by microorganisms considered of clinical importance, contributing to a possible spread of diseasecausing microorganisms among dentists and patients.