Objective: We investigated the association between autoimmune and chronic inflammatory disorders and several cancer types including lymphomas. Methods: All cancer patients diagnosed between 1995 and 2007, aged 15 to 90 years, and registered in the Eindhoven Cancer Registry were included in this study. Co-morbidity at diagnosis was recorded by qualified registry personnel who obtained the information from the clinical record. We determined the prevalence of rheumatoid arthritis (RA), chronic inflammatory bowel diseases, connective and vascular tissue diseases, ulcers of the stomach and duodenum, hepatitis, human immunodeficiency virus (HIV), and tuberculosis (TBC) among newly diagnosed patients with lymphoma and compared this with the prevalence among patients with all other cancers. Results: The prevalence of most of these co-morbidities was higher in patients with lymphomas than those with other malignancies. RA was more often present in newly diagnosed patients with most lymphomas, ulcers of stomach and duodenum in patients with marginal zone lymphoma, hepatitis in case of diffuse large B-cell lymphoma, HIV with aggressive B-cell lymphoma, and TBC with mantle cell lymphoma. Conclusion: This study confirms the positive association between autoimmune and chronic inflammatory disorders and the various lymphoproliferative malignancies, suggesting either a shared etiology or pathogenesis or a direct causal relation. This is a fairly new method to study aetiological questions about cancers in a population-based cancer registry. (C) 2010 Elsevier B.V. All rights reserved.