In a case of pseudoxanthoma elasticum (PXE), Bruch's membrane was studied histochemically, ultrastructurally and by element analysis. Two kinds of calcifications were observed, one composed of hydroxyapatite and the other of CaHPO4. They were seen in the scar tissue of angioid streak areas and in the membrane outside these areas, respectively. Furthermore, a thready material was found in the membrane as well as an increased amount of acid mucopolysaccharides. The genesis of the calcifications and the pathogenesis of angioid streaks are discussed. The author is in favor of a malformed collagen as the basic defect in PXE.