Disturbances in calcium and bone metabolism after gastrectomy have long been recognized. It has been suggested that due to impaired calcium absorption after gastrectomy, serum calcium is decreased, being counter-regulated by parathyroid hormone release and 1,25-(OH)2-vitamin D formation. Both parathyroid hormone and 1,25-(OH)2-vitamin D are known to release calcium from bone, resulting in bone mass loss and increased fracture risk in some of the gastrectomized patients. No therapy is currently generally agreed on, although supplementation of vitamin D and calcium has been suggested repeatedly. A review on the current understanding of calcium and bone metabolism after gastrectomy is given.