PSEUDOACHONDROPLASIA is a term used by Lamy and Maroteaux in 19601 and later by Rubin2 to describe a category of bone dysplasia which combines features of both achondroplasia and true Morquio's disease. It resembles achondroplasia in that there is marked shortening of the extremities. It differs from true achondroplasia, however, in that typical cranial and facial features are absent, discovery may be delayed until the second year of life, and abnormalities of the vertebrae and pelvis characteristic of Morquio's disease are present. Since these features can be explained by a primary defect in the articular cartilage of the epiphysis and vertebrae with secondary involvement of the epiphyseal plate, it is classified as a type of spondylo-epiphyseal dysplasia.3 Recent investigations of cases of spondylo-epiphyseal dysplasia of Morquio's type have shown corneal opacities, dental abnormalities, and the presence of keratosulfate in the urine.4-7 Similar investigations of pseudoachondroplasia have