Background <p>Irrational beliefs, considered central cognitive vulnerabilities, are strongly associated with increased distress levels, impacting a broad range of psychological and physiological responses. While the association between irrational beliefs and mental disorders is well-established, fewer studies have explored their relationship with inflammation, which represents an immune-mediated process associated with a wide range of chronic conditions. Moreover, in rheumatologic diseases, inflammatory processes represent the primary mechanism underlying the development of characteristic symptoms. This study aims to examine the correlations between distinct types of irrational beliefs and specific biomarkers of inflammatory responses associated with rheumatic diseases.</p> Method <p>The study included 49 participants diagnosed with various rheumatic diseases. Biomarkers assessed were erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). The Attitudes and Beliefs Scale–Second Edition (ABS-II) was used for measuring the levels of irrational beliefs.</p> Results <p>ESR showed positive correlations with awfulizing and irrational beliefs related to comfort. No significant correlations were found with CRP.</p> Conclusion <p>Highlighting significant associations between ESR and irrational beliefs, this research underscores the relationship between psychological factors and physical health in chronic medical conditions, such as rheumatic diseases. These findings offer a basis for future studies investigating the mechanisms linking irrational beliefs and inflammatory processes, further emphasizing the clinical relevance of addressing irrational beliefs in patient care.</p>