Rickets is a worldwide bone disease that is associated with disorders of calcium and phosphate homeostasis and can lead to short stature and joint deformities. Osteomalacia is a major metabolic bone disease that results from a chronic and severe deficiency of vitamin D or phosphate from any cause after growth has stopped. A deficiency of vitamin D or phosphate leads to defective bone mineralization and generalized or localized vague bone pain in various parts of the skeleton and / or proximal muscle weakness. Rickets and osteomalacia are two different clinical diseases with impaired bone mineralization. Rickets occurs throughout the growing skeleton in infants and children, while osteomalacia occurs in adults after fusion of the growth plates. Rickets and osteomalacia are increasingly common in Saudi Arabia, with vitamin D deficiency being the most common etiological cause. Early skeletal deformities can occur in infants, such as soft, thin skull bones, a condition known as craniotabes. In adults, as a result of demineralization, the bones become less rigid (soft bone) with pathological fractures. The diagnosis of both diseases is based on the medical history and physical examination, radiological characteristics, and biochemical tests. Management depends on the underlying etiology.