An ultrastructural study of the dermis in a case of acrogeria is presented and compared with a healthy control of same age and sex. The overgrowing orceinophil material was mainly pseudoelastic. The collagen was hypoplastic and mostly immature. Inside and outside the fibroblasts a lot of a granulofilamentous substance intermingled with pseudoelastin and immature collagen was observed. Fibroblast cytoplasm was often distended by ergastoplasmic vacuoles filled with granulo filamentous substance and contained numerous pseudomyelinic bodies. These abnormalities suggest that acrogeria might be a fibroblast disease.