We report 7 cases of „silent“ form of hereditary spherocytosis observed among members of 4 different families. Silent form of hereditary spherocytosis occurred in 5,4% of all patients with hereditary spherocytosis treated in our institute. The patients with silent form featured normal Hb level and red blood cell count, normal or slightly elevated reticulocyte count and bilirubin level. Osmotic resistance of red blood cells was decreased and autohemolysis was increased, nevertheless, the differences from normal range were less prominent than in patients with mani- fest form of the disease. Analysis of red cell membrane revealed deficiency of band 3 protein in all cases of silent form of hereditary spherocytosis.

        Key words: Hereditary spherocytosis - „Silent form“ of hereditary spherocytosis - Red cell mem- brane protein deficiency.