Abstract: Crystalline and amorphous insoluble calcium salts of bisphosphonic acids may be formulated to provide compositions suitable for I.M. (intramuscular) and S.C. (subcutaneous) administration. As compared to solutions of the soluble salts of bisphosphonic acids, suspensions of the crystalline and amorphous calcium salts provide slow systemic release of the bisphosphonic acid and reduce tissue damage and localized pain and irritation when used in the treatment of disturbances involving calcium or phosphate metabolism, in particular, the treatment and prevention of diseases involving bone resorption, especially osteoporosis, Paget's disease, malignant hypercalcemia, and metastatic bone disease.