BackgroundWorking in accident management centers and medical emergencies makes employees face psychological tensions and leads to a decrease in their work quality and endangering the lives of patients. Therefore, any solution to reduce their tension will be valuable. This study was conducted to investigate the effect of acceptance and commitment-based therapy (ACT) on work-related rumination and job fatigue among the employees of the Emergency and Medical Accident Management Center of Alborz Province, Iran.MethodsThis study is an experimental research with intervention and control groups conducted between January 16, 2019, and July 8, 2019. Sixty-four employees were selected based on the entry criteria and randomly assigned to two groups. People in the intervention group participated in 8 sessions of 2-hour therapy based on acceptance and commitment. Questionnaires for demographic information, work-related rumination, and occupational recovery/exhaustion were used to collect data. The intervention was conducted with univariate and multivariate covariance analysis.ResultsThe findings showed that the average job fatigue reached 16.78\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:\\pm\\:$$\\end{document} 11.44 from 37.06 ± 16.70 in the pre-test with a decrease of 20.28 points. Also, the average of all rumination dimensions related to work decreased in the post-test. The findings showed that the effectiveness of treatment based on acceptance and commitment therapy was confirmed on job fatigue and all its components and all dimensions of work-related rumination (p < 0.05). The partial eta square index was greater than 0.14 in all cases and showed the significant effectiveness of the intervention on all components of work-related rumination and job fatigue.ConclusionTreatment based on acceptance and commitment reduced rumination and job fatigue. It is recommended to practice this intervention to improve personnel’s mental health and the quality of services provided to patients.Clinical trial numberNot applicable.