Rationale: The spread of foam sclerotherapy has resulted in the renaissance of sclerotherapy as a non-invasive treatment method for varicosis. An expanded European expert committee meeting in Tegernsee in April 2006 was prompted by new findings and continuous further development of the method and worked especially on the topics "The role of (duplex) ultrasound in Foam sclerotherapy" and "Evaluation of therapeutic effects of foam Sclerotherapy". It was felt that these criteria are "non-specific" to foam sclerotherapy and would possibly also be suitable for other endovenous ablative procedures. The organisers of the 2nd European Consensus Meeting on foam sclerotherapy (2nd ECMFS) were then asked to publish these recommendations in this separate publication. The entire recommendations of the 2nd ECMFS are published in an extensive overview in this journal (VASA 2008; 37; Supplement 71: 1–32). Methodology: The 29 participants were sent a comprehensive questionnaire in advance covering all the relevant aspects of foam sclerotherapy. The organisers drew up various preliminary statements on the basis of the results. During the meeting itself the participants revised and/or approved and/or rejected these statements. For the "non-specific" topics, two working groups were given the task of conducting the concluding assessment of these items. Their final results were presented in March and April 2007. Results: For foam sclerotherapy, duplex ultrasound is important in pre-treatment diagnosis, treatment monitoring/guidance, post-treatment efficacy evaluation and surveillance. In the pre-treatment diagnosis of varicose veins, the exact localisation of the insufficient saphenous, communicating and perforating veins is important. Duplex ultrasound is the accepted gold standard for this purpose. The application of ultrasound imaging during foam sclerotherapy increases the safety of accessing the vein in certain indications, and it can help when making a decision concerning the foam volumes to be injected, the patients’ position or specific movements the patients should perform. Following treatment, the findings of duplex ultrasound, the clinical findings and the patients’ symptoms can be arranged according to the recommended definitions. This allows grading of the therapeutic outcome and enables a better comparability between different treatment protocols or different treatments. Besides the evaluation of treatment success, duplex ultrasound is the method of choice to exclude or confirm complications such as deep venous thrombosis or disease progression.