This study was carried out to the effectiveness of metacognition therapy on marital quality of women in the city of Isfahan. The research design employed was quasi-experimental with pretest–posttest with control group. The study population included all married women visiting consultation centers in the city of Isfahan during March 2018–March 2019. The sampling method was nonrandom voluntary sampling used to select 30 participants who were then randomly divided into experiment and control groups (15 individuals each). The research tool was the Revised Dyadic Adjustment Scale. The experiment group participated in eight sessions of metacognition therapy, each lasting 90 min. The result of covariance analysis showed that metacognition therapy has been effective in improving the marital quality of the participants. Using this treatment plan can result in improved marital quality and marital satisfaction and therefore improve the relationship of couples. Therefore, the results of the current study can provide empirical support for the use of metacognition therapy to improve marital quality