Achondroplasia is a rare disease and characterized by the combination of short extremities with an enlarged head and a trunk approximating normal size. We had experienced 4 cases of achondroplasia; they all showed stunted growth, short arms and legs, prominent forehead, flattening of the bridge of the nose and moderate degree of kyphcsis and one case was associated with hydrocephalus. X-ray showed the thickness of the bones and their irregular epiphyseal ends such as cupping, flaring and spurs. Intelligence seemed to be normal except one case. We had seen those patients at the age of 8 months, 6 months and 1year, 7months and 2 years, confirming achodroplasia by clinical, X-ray survey and biochemical study. Review of the references concerning achondroplasia was made briefly.