The present study aimed to explore the role of dysfunctional metacognitive beliefs in Eating Disorders (EDs) and their potential associations with core and comorbid symptoms. The Metacognition Questionnaire-30 (MCQ-30), the Eating Disorder Examination Questionnaire 6.0 (EDE-Q), the Hospital Anxiety and Depression Scale (HADS) and the Maudsley Obsessive- Compulsive Inventory (MOCI) were used to evaluate 44 Anorexia Nervosa (AN), 50 Bulimia Nervosa (BN) patients and 37 controls. Patients featured more dysfunctional metacognitive beliefs which positively correlated with ED and comorbid symptoms. Both AN and BN patients had higher scores than healthy controls on MCQ-30 total score, Positive Beliefs about Worry, Negative Beliefs about Thoughts Uncontrollability and Danger and Need to Control Thoughts. AN patients also featured higher scores than healthy controls on Cognitive Self-Consciousness. No statistically significant difference was found between the two clinical groups in MCQ-30 total and subscale scores. Among metacognitive beliefs, Negative Beliefs about thoughts Uncontrollability and Danger showed the stronger correlations with core EDs symptoms, (coefficients ranging from 0.24 to 0.40), followed by Need to Control Thoughts (coefficients ranging from 0.22 to 0.38). Dysfunctional metacognitive beliefs were also significantly positively correlated with HADS-Anxiety, HADS-Depression and MOCI Total, in a similar manner. Dysfunctional metacognitive beliefs also predicted 19%, 35%, 20%, and 21% of the variance in Global EDE-Q, HADS-Anxiety, HADS-Depression and MOCI Total scores respectively, in regression analyses. Nevertheless, mediation analysis indicated that the relationship between Negative Beliefs about thoughts Uncontrollability and Danger and core EDs symptomatology as measured by EDE-Q, was not mediated by comorbid anxiety, depression and obsessionality. As a result, dysfunctions in metacognitive beliefs may reflect a common, trans-diagnostic path in AN and BN patients, towards a wide range of symptoms, both core and comorbid.