Rickets is a disorder of growing skeleton due to deficiency of vitamin D, calcium deficiency and chronic hypophosphatemia. Their Growth plate is divided into various zones: Resting zones, proliferative zone, transformation zone, ossification and remodeling. Vitamin D deficiency leads to hypocalcemia, hypophosphatemia, secondary hyperparathyroidism and defective mineralization of bone which in growing skeleton results in rachitic changes and impaired linear growth along with hypotonia. The low calcium intake precipitates the vitamin D deficiency by increasing the catabolism of 25(OH) vitamin D by 24-hydroxylase. X-linked hypophosphatemic rickets cause mutation in phosphate regulating gene with homology to endopeptidase on X-chromosome. Hypophosphatemia is caused by the FGF-23. Renal tubular acidosis is due to renal phosphate wastage and associated systemic acidosis. Radiological and biological features of rickets are also discussed. It can be treated by oral phosphate without active vitamin D supplementation and calcitriol.