Purpose: This study aims to analyze the effect of nail polish applied by operating room nurses on bacterial colonization after surgical hand washing.,Materials and Methods: This is a self-controlled, experimental study in which the before and after values of the same group were analyzed. This study was conducted on 33 operating room nurses. The glove juice method was used to measure bacterial colonization on the nurses' hand flora. The data were collected using the Introductory Information Form for Nurses and the Data Recording Form. The data were analyzed using descriptive statistical methods along with the Wilcoxon test.,Results: Of the nurses, 54.56% had a bachelor's degree, 78.8% had been working as a nurse for at least 11 years, and 63.7% had been working as an operating room nurse for at least 11 years. Of them, 66.7% had nails shorter than 2 mm. and 60.6% sometimes used moisturizer. No statistically significant difference was found between the amount of bacteria in the samples obtained from the nurses' hands with and without nail polish after surgical hand washing.,Conclusion: The findings showed that freshly applied nail polish has no effect on bacterial colonization.