Quantitation of bone mineral by photon absorptiometry is a simple and accurate method for determining changes in bone volume and mineral content in serial studies. An extension of the scintillation camera method for studying such changes in the calcaneous is described. This technique is applicable to large areas of bone, thereby minimizing the effect of repositioning errors. Using a 40-mCi 241Am sheet source, a 2.1% reproducibility in bone phantoms and a 2.4% reproducibility in normal patients was achieved. Several case studies are presented to illustrate sensitivity and clinical application of the method. Although bone mineral determinations are now performed in a limited number of health care facilities, the scintillation camera method described in this report could increase the availability of these determinations significantly.