Introduction <p>Sleep quality is a crucial aspect that can affect the health, job performance, and safety outcomes of operating room employees. However, the social and work-environmental factors that predict sleep quality remain unclear. This study aimed to determine the role of social relational quality and ethical climate as the predictors of sleep quality in employees of the operating room using hierarchical linear regression analysis.</p> Methods <p>This cross-sectional and multi-center study was conducted on 232 operating room employees. Data were collected using the social relational quality scale, Hospital Ethical Climate Survey, and Pittsburgh Sleep Quality Index. Pearson’s correlation coefficient, ANOVA, t-test, and hierarchical multiple linear regression were used to analyze the data.</p> Results <p>The mean scores of social relational quality and standardized ethical climate were 54.80(SD = 6.35) and 3.40(SD = 0.68) in the operating room employees. The mean score of sleep quality was 6.70(SD = 3.66) which was in the poor range. The last step of regression analysis showed that profession (β=˗0.22, <i>p</i> = .02) and social relational quality (β=˗0.20, <i>p</i> = .03) had a significant proportion of the variance of sleep quality. Based on the model, work experience, profession, social relational quality, and ethical climate accounted for 15% of the changes in sleep quality in the operating room employees.</p> Discussion <p>This study indicated that more than half of the operating room employees reported poor sleep quality. Moreover, profession and social relational quality were the predictors of sleep quality. Conducting interventions to improve social relational quality might enhance the sleep quality of operating room employees.</p>