This study aims to assess by biological markers the in vivo consequences of foam sclerotherapy (FS) of saphenous veins. The secondary objective of this randomised controlled trial (RCT) is to compare results of two randomised groups: with or without post-treatment compression.Forty patients with incompetent great or small saphenous veins underwent ultrasound-guided FS. Randomisation was conducted immediately after sclerotherapy to two parallel groups, one (CG) with compression stockings and the other (WCG) without compression. A laboratory work-up was done on days 0 (before sclerotherapy), 1, 7, 14 and 28. The studied markers were: fibrinogen, factor VIII, thrombomodulin, thrombin-antithrombin complex, D-dimers, platelet factor 4 and troponin.General data repartition was homogenous for CG and WCG. Twenty patients were included in each group (females 90%; mean age 58 years). On day 28 (D28), the occlusion rate of the veins was 100% in both groups. In all the samples (D0-D28), apart from a moderate D-dimers' increase at D1-D14, no significant biological change was observed in either the WCG or the CG groups.In terms of inflammation and coagulation, FS seems to have a minimal effect on peripheral blood, either with or without post-treatment compression and does not appear to have an effect on the myocardial risk.