Central retinal vein occlusions (CRVOs) are rarely treatable; most therapy is directed towards prevention or treatment of complications. Bilateral CRVO can be due to serum hyperviscosity, which affects 15% of all patients with Waldenstrom's macroglobulinaemia (WM). Although previously reported in a handful of cases, bilateral CRVO is a rare presenting feature.Illustrated case reports of three patients presenting with bilateral CRVO due to undiagnosed WM.Plasma exchange, which successfully restored vision in two patients, was followed by long-term cytotoxic therapy.Plasma electrophoresis should be performed in all patients with retinal vein occlusions to exclude a paraproteinaemia. In patients with bilateral venous changes, there should be a very high level of suspicion of hyperviscosity, with the possibility of effective early therapy.