No association was found between CLDN3 and 5 levels and WFNS score, 3-month mRS, age, sex, comorbidities, inflammatory markers, or DCI.<h4>Conclusion</h4>Elevated serum CLDN3 and especially CLDN5 levels reflect hemorrhage extent and potential BBB disruption in aSAH. This evidence concerns the gene CLDN5 and hemorrhage.