Introduction: The aim of this study was to investigate the relationship of attachment styles and mental health with marital adjustment in couples.Method: This correlation study enrolled 700 couples consisting of 350man and 350 women of 20 to 40 years old who lived in Ardebil city. To collect the data, Bartolommeo and Horvitz attachment style questionnaire, Mental Health questionnaire (SCL-90-R) and Spaniers Marital adjustment questionnaire (DAS) were employed. The data were analyzed using Pearson correlation coefficient and step-by-step regression.Results: Results showed that there is a positive correlation between mental health and marital adjustment in people with insure, preoccupied and dismissing attachment styles. However, there is a negative correlation between mental health and marital adjustment in people with fearful attachment style. Furthermore, we showed that mental health and attachment style explain roughly 13 percent of adjustment variance.Conclusion: These results can be used in premarital consultation, determining attachment style, or couple's mental health in order to predict their marital adjustment. Such practice will assist in training couples to improve their satisfaction and adjustment.