The objective of this chapter is to introduce the rickets. Rickets is a condition that affects bone development in children. It causes the bones to become soft and weak, which can lead to bone deformities. Rickets in adults is known as osteomalacia or soft bones. Metabolic disorders of bone in children are characterized by generalized reduction in bone mass due to subnormal osteoid production, subnormal osteoid mineralization or excessive rate of deossification. Dietetic deficiency of vitamin D and calcium may be partly responsible for such rickets. Clinical diagnosis of rickets, pathoanatomy of rickets, renal rickets, familial hypophosphatemic rickets, vitamin d-dependent rickets, renal osteodystrophy, rickets in liver disorders, rickets associated with prematurity, causes of rickets, various clinical presentations, laboratory diagnosis and treatment of rickets are also discussed in this chapter.