Background: Many home-dwelling elderly use medical compression stockings to prevent venous insufficiency, deep venous thrombosis, painful legs and leg ulcers. Assisting users with applying and removing compression stockings demands resources from the home based health services, but the effects are uncertain. This systematic review aims to summarize the effects of preventive use of medical compression stockings for patients with chronic venous insufficiency and swollen legs. Methods: We conducted a search in six databases (Epistemonikos, Cochrane Database of Systematic Reviews, MEDLINE, Embase, CENTRAL and CINAHL) in March 2018. Randomized controlled trials evaluating the preventive effects of European standard compression stockings class 3 or 2 for elderly with chronic venous insufficiency and swollen legs were included. Primary outcomes were thrombosis, leg ulcers and mobility. Secondary outcomes were other health related outcomes, e.g. pain, compliance. We assessed risk of bias in the included studies and used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool for evaluating the overall quality of evidence. Results: Five randomized controlled trials met the inclusion criteria. Comparing compression stockings class 2 to class 1, meta-analysis showed a reduction in leg ulcer recurrence at 12 months (RR 0.52; 95% CI 0.30 to 0.88). The quality of evidence was assessed as moderate by GRADE. One study (100 participants) did not detect a difference between compression stockings class 3 versus class 2 on ulcer recurrence after six months (RR 0.64; 95% CI 0.20 to 2.03). In another study, patients wearing class 3 compression stockings had lower recurrence risk compared with patients without stockings (RR 0.46; 95% CI 0.27 to 0.76) at six months and (RR 0.43; 95% CI 0.27 to 0.69) at 12 months. We found no difference between class 2 and class 1 stockings on subjective symptoms of chronic venous insufficiency or outcomes of vein thrombosis or mobility. Conclusion: Compression stockings class 2 probably reduce the risk of leg ulcer recurrence compared to compression stockings class 1. It is uncertain whether the use of stockings with higher compression grades is associated with a further risk reduction. More randomized controlled trials on vein thrombosis and mobility are needed.