Calcium and vitamin D are important for maintenance of homeostasis of skeletal system, therefore it is important to ensure their correct input in the organism. Calcium is present in many types of food, especially in dairy products, and vitamin D is naturally synthesized during the exposure to sunlight. Certain conditions and illnesses, such as old age and osteoporosis, require a higher input of calcium and vitamin D and this can be achieved with supplements. Although these supplements have many benefits, studies have shown that the effects of calcium and vitamin D supplements can also have side effects and this questions the safety of their usage. Some of the side effects of using calcium and vitamin D, which is essential for calcium absorption, include not only gastrointestinal disorders such as constipation and bloating, but also a risk of cardiovascular diseases as well as a higher risk of developing kidney stones. Objectives: Purpose of this research is to take a look at scientific and professional papers on Calcium and Vitamin D supplements, their positive effects as well as their side effects. Materials and methods: For the purpose of this specialist thesis a systematic and retrospective overview of scientific and professional papers on Calcium and Vitamin D supplements has been made, using PubMed and Mediline database, also following the National Osteoporosis Foundation guidelines. Results: This thesis gives a full overview of Calcium and Vitamin D, their usage, sources, recommended daily dosage, positive effects and side effects. Conclusion: There is an increase in patients suffering from osteoporosis and its occurrence and effects can be prevented with correct usage of Calcium and Vitamin D supplements. A number of research have shown that intake of these supplements, if not taken properly, can also have negative outcomes and for this reason it is important to know the benefits and side effects of using these supplements in order to ensure a maximum benefit of supplements usage with a minimum risk of side effects.