Imbalance of bone resorption and bone formation is responsible for osteoporosis that is characterized by decreased bone mass and mineral density. The aim of this study was to evaluate the available data that could clarify the effectiveness and safety of supplementations with calcium and vitamin D, alone or in combination, to slow down bone loss in postmenopausal and elderly women. Using search key words, we performed a research both in the PubMed and Cochrane Library in order to find all meta-analysis, prospective and randomized clinical studies published from 2000 to 2014 that had investigated the effectiveness of calcium and vitamin D in the treatment of osteoporosis. At the moment it is not possible either to provide reassurance that calcium supplements given with vitamin D do not cause adverse cardiovascular events or to link them with certainty to increased cardiovascular risk. According to the data now available, vitamin D, at dosage of at least 800 IU/day, alone or in combination with antiresorptive drugs, should be administered in osteoporotic and osteopenic patients for a primary and secondary prevention. Further studies are needed and the debate remains ongoing. However, every administration needs the calculation of the absolute fracture risk of the patient. Especially considering the high cost of osteoporosis prevention, more studies are mandatory to clarify indications and contraindications.