The objective of this investigation was to evaluate the efficacy of metacognitive therapy in the treatment of cognitive-attentional syndrome, catastrophizing, and pain intensity in women with fibromyalgia. This investigation was a practical and semi-experimental study that included a pre-test-post-test design and a control group. 42 patients were selected from the statistical population of the study, which consisted of women with fibromyalgia who visited specialized rheumatology and orthopedic clinics in Tehran in April and May 2022. The selection was based on the definitive diagnosis of fibromyalgia, and used the available sampling method. Then, the participants were randomly assigned to the experimental and control groups. The Cognitive Attention Syndrome Scale (CAS-1), Pain Catastrophizing Scale (PCS), and Pain Intensity Scale Questionnaire (SCPQ) were employed to evaluate the participants. The information was analyzed and the research hypotheses were addressed using descriptive and inferential statistics in SPSS-26. The mean and standard deviation were employed at the descriptive level. The Shapiro-Wilk Test was implemented to evaluate the normality of the variable distribution at the inferential level, while the Levene’s Test was implemented to evaluate the homogeneity of variances. Additionally, Multivariate Analysis of Covariance (MANCOVA) and Univariate Analysis of Covariance (ANCOVA) tests were used to examine the research hypothesis. The analysis of the data from the pre-tests and post-tests obtained from the participants at a significant level (P<0.01) revealed that metacognitive therapy significantly reduced attentional cognitive syndrome (effect size of 0.85), pain catastrophizing (effect size of 0.89), and pain intensity (effect size of 0.86, 0.83, 0.69) in fibromyalgia patients. The findings indicate that metacognitive therapy alleviates cognitive-attentional symptoms, catastrophizing, and pain intensity in fibromyalgia patients
