Clinical specimens of plasma and urine were obtained to observe the difference between OSA patients and healthy controls and diagnostic accuracy of CLDN molecules for OSA.<h4>Results</h4>CLDN1, CLDN2, and CLDN3 molecules in plasma and urine decreased in OSA patients (both <i>p</i> < 0.05). This evidence concerns the gene CLDN1 and obstructive sleep apnea syndrome.