Objectives: Foam sclerotherapy of varicose veins has recently proven to be an effective, economic and safe treatment modality. The present Study attempts to evaluate the haemodynamic changes after sclerotherapy in addition to the clinical results. Methods: In a prospective observation trial, 67 sites (2/3 of which were recurrent varicose [RV] veins after previous treatment) in 53 patients were treated with polidocanol foam, and the results were assessed clinically, by duplex, photoplethysmography and strain gauge plethysmography. Results: With the exception of two sites (3.0%), all treatments resulted at least in an improvement, and about 80% of the treated veins were completely occluded as demonstrated by duplex ultrasound examination. The haemodynamical results accordingly reflected a significant improvement of the venous function. Patients with post-thrombotic syndrome showed poorer results. Conclusion: Foam sclerotherapy is a highly effective and safe method for the treatment of primary and RV veins.