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The mechanism of calcification of bone is still not clearly understood. Irving (1958) demonstrated the presence of sudanophilic zones in the region of clacification fronts in calcifying tissues extracted with pyridine. Since then these zones have been studied extensively to find out the nature of material which takes up the Sudan B Stain. We have studied these zones in cancellous as well as cortical bones of 8o osteomalacic patients.