Objective:To determine the direct action of calcium sensing receptor (CaSR) on both long bone and cartilage mineralization of mice. Methods:The femur and tibia of both 3-day-old wild-type and CaSR gene knockout mice from the same brood were transplanted into the latissimus dorsi muscle of 8-week-old wild type mice with the same parents of the 3-day-old mice. After 4 weeks,the femur and tibia were analyzed with X-ray and histology methods. Results:CaSR knock-out mice exhibited growth retardation and the hypertrophic zone of cartilage was obviously wider than that of the wild-type mice (P < 0.001). Conclusion:CaSR have a direct promoting action on long bone growth,and can stimulate the mineralization and ossification of hypertrophic chondrocytes.