The reemergence of vitamin D deficiency in the industrialized countries resurrects the "threat" of nutritional rickets, especially among pediatric populations, a fact that may lead to underdiagnosis of hereditary rickets. Today, hereditary rickets may be subdivided into two main groups according to their biochemical profile: the one associated with defects in vitamin D synthesis and action and the second associated with abnormal phosphorus metabolism. The classification of the patients in a particular group of hereditary rickets is determinative of the treatment to follow. This review, through the recent advances on vitamin D and P metabolism, discusses the molecular and biochemical defects associated to each group of inherited rickets, as well as the clinical phenotypes and the recommended therapeutic approaches.