The microscopic pathology of the epiphyseal cartilage plates and adjacent bone in seven patients with dwarfism and skeletal deformities has been reported. In two of the patients the clinical picture is clearly that of Morquio's syndrome; in two others, the picture resembles dysplasia epiphysalis multiplex; and in the remaining three there are some of the roentgenographic criteria of both of these conditions. Similar pathological changes were present in the epiphyseal cartilage plate in all seven cases. The essential defect is in the epiphyseal chondrocytes which fail to reach the zone of ossification in adequate numbers or in a fully developed hypertrophic condition, resulting in defective enchondral ossification. Deficient metaphyseal osteogenesis results from inadequate chondrocyte proliferation and maturation. Cystic amid mucoid degeneration of cartilage matrix and areas of aberrant epiphyseal ossification are also noted. None of the storage phenomena of Hurler's syndrome are present. The pathological findings in dysplasia epiphysalis multiplex, Morquio's disease, and achondroplasia relate directly to epiphyseal chondrocyte dysfunction. These conditions might therefore be grouped together under the term chondrogenic dwarfism to indicate their common pathological relationship. The epiphyseal cartilage changes in these coniditions are readily distinguished from those usually associated with dietary deficiencies and endocrine disorders in human subjects.