In recent years, anemia in nephrotic syndrome has been the subject of investigation. In addition to erythropoietin deficiency the anemia of proteinuric patients is tried to be explained by a shortened erythrocyte lifespan due to decreased red deformability. Twelve proteinuric patients were compared with two age and sex-matched control groups (anemic and healthy). Red cell deformability and viscosities at three different shear rates were evaluated. It is demonstrated that in proteinuric patients red cell deformability and blood viscosities at different shear rates were decreased.