Tight junctions (TJs) provide a barrier function, inhibit solute and water flow through the pericellular space. Aim: Analysis of the expression pattern of the TJ-molecules occludin (OCLN), claudin-1 (CLDN-1), -3 (CLDN-3), and -5 (CLDN-5) on mRNA and protein level in patients with oedema, venous leg ulcers and healthy controls. Material, methods: Biopsy specimens were taken in healthy individuals and in patients before and four weeks after compression therapy. The expression of mRNA was determined by densitometry after using reverse transcriptase and polymerase chain reaction (RT-PCR), the expression of protein after western blot from tissue specimens. Results: Quantification revealed a diminished expression for CLDN-1 (p<0.01) and CLDN-5 (p<0.01) in patients with chronic venous insufficiency in comparison with healthy controls on mRNA as well as protein level. No statistical differences were detected for OCLN and CLDN-3 between the oedema group and healthy controls. There was a significantly elevated expression (p<0.01) on mRNA and protein level between the leg ulcer group and healthy controls for OCLN and CLDN-3. Densitometric quantification revealed a more significantly elevated expression (p<0.01) for CLDN-1 and CLDN-5 on mRNA and protein level after four weeks of compression therapy in comparison with that prior to treatment for the group with oedema as well as for the group suffering from leg ulcer. Conclusion: Compression therapy tightens the paracellular barrier via elevated expression of specific TJs. It prevents the progression of chronic venous insufficiency because its effect on permeability preventing the entrance of fluid into the perivascular tissue.