Hermansky-Pudlak syndrome is a hereditary disease with an autosomal recessive mode of inheritance, characterized by the triad of tyrosinase-positive oculocutaneous albinism, a hemorrhagic diathesis resulting from storage pool-deficient platelets, and accumulation of ceroid/lipofuscin-like material in various cells and tissues and in the urine. The basic defect in this syndrome remains unknown. It is believed that the primary defect may involve membranes of the platelet-dense bodies and the melanosomes. Recently a defective calcium uptake system and low activities for membrane-associated thioredoxin reductase have been shown in Hermansky-Pudlak syndrome, and their possible role in the pathomechanism of this disorder is discussed.