Cystic fibrosis (CF) is an autosomal recessive genetic disorder. The disease affects all secretory epithelia including the eye and belongs to the group of ocular surface epithelial diseases, termed keratoconjunctivitis sicca that develop in dry eye. In the pathogenesis of dry eye, inflammation plays a crucial role. The aim of this study was to assess the potential role of MIP-1beta in the pathogenesis of dry eye syndrome in patients with CF. We assayed MIP-1beta levels in tear fluid and serum of 28 patients with CF and 27 controls by ELISA. The ophthalmic examinations including the tests for dry eye were used to study the ocular surface. The tear levels of MIP-1beta in the CF patients were significantly higher than those in the controls. Dry eye syndrome was observed in 10 (36%) CF patients. The tear fluid levels of MIP-1beta were significantly raised in CF patients with dry eye syndrome compared with CF patients without dry eye symptoms. Our results suggest a crucial role of CCL4/MIP-1beta in the development of dry eye syndrome in CF patients and immunopathogenesis of ocular surface changes in this disease. Clarification of the role of CCL4/MIP-1beta in the pathogenesis of ocular findings in CF patients will be useful in establishing immunotherapeutic strategies for this disease.