Vitamin D is essential for maintaining a healthy mineral and bone metabolism. It stimulates calcium and phosphate absorption by the intestine, regulates bone metabolism, and negatively controls PTH secretion through the endocrine action of its active metabolite calcitriol. Vitamin D also possesses a variety of effects unrelated with mineral and bone metabolism, including the regulation of arterial blood pressure and the prevention of cardiovascular complications, modulation of immunological responses, regulation of insulin production and prevention against diabetes, protection against certain cancers, renoprotection, and other beneficial actions. This article provides an update review of the sources and pharmacological characteristics of natural vitamin D compounds, their most clinical uses, and their most important clinical results.