This study explores the impact of social capital on professional ethics of nurses in Mashhad city. Correlation and type applied research population was selected as the nurses working in two hospitals (Qaim and Razavi) in Mashhad. Of these, 580 were selected as random samples by 230 individuals. Two standard questionnaires (professional ethics, social capital) were used for data gathering. The reliability of these questionnaires with Cronbach's alpha higher than 0.86 was good and the data were analyzed using SPSS and smartpls2. The theoretical approach of this study was a combination of theories. The results showed Social capital has a positive and significant effect on professional ethics of nurses in Mashhad city. The coefficient of determination of R2 for dependent variable shows that social capital of dependent variance (professional ethics) can be explained. Manuscript profile