Objective of the study. To estimate the content of type IV and VI collagens in the walls of the superficial and deep crural veins of the patients presenting with primary varicose veins. Material and methods. We studied the segments of great saphenous and posterior tibial veins in 18 patients suffering from primary varicose veins after phlebectomy and resection of posterior tibial veins. The fragments of great saphenous and posterior tibial veins (7 samples of each) that served as controls were obtained from the subjects who had died from causes other than primary varicose veins. Expression of type IV and VI collagens in the main structural components of the venous system was evaluated based on the results of immunohistochemical staining with the use of concentrated lyophilized monoclonal antibodies against type IV and VI collagens «Novocastra». Results. The positive expression of type IV collagen was observed at an area of 0.000760 (0.000566; 0.0001177) mcm2 of the affected great saphenous vein fragments compared with 0.000973 (0.000789; 0.0001420) mcm2 in control samples. In the walls of affected posterior tibial veins the area of type IV collagen expression was significantly smaller, namely 0.000577 (0.000411; 0.000863) mcm2, than in control samples  — 0.000696 (0.000574; 0.000827) mcm2. The positive expression of type VI collagen was observed at an area of 0.006036 (0.004729; 0.007869) mcm2 of varicose great saphenous vein fragments compared with 0.003538 (0.002516; 0.004647) mcm2 in control samples. In the walls of affected posterior tibial veins the area of type VI collagen positive expression was significantly greater, namely 0.004395 (0.002775; 0.006437) mcm2, than in control samples — 0.003259 (0.002634; 0.0044197) mcm2. Conclusion. In the patients presenting with primary varicose veins and deep vein vulvular incompetence, type IV collagen content in the walls of great saphenous and posterior tibial veins decreases whereas the content of type VI collagen in the same vessels increases in comparison with the respective normal values.