Two patients presenting ocular complications of hyperviscosity syndrome in Waldenström's macroglobulinemia have been treated by plasmapheresis after inefficiency of immunosuppressive therapy. Plasma exchange seems an useful treatment as shown by clinic and angiographic improvement. In each case improvement of retinopathy was correlated with decrease of serum IgM level and blood viscosity measured by isotopic method. Fluorescein angiography, easily repeated, seems a very good method for following hyperviscosity syndrome in Waldenström's macroglobulinemia.