We report a sibship of a sister and brother with osteoporosis-pseudoglioma syndrome. Several other family members became blind or showed signs of bone involvement. There was considerable consanguinity in the pedigree. The proband was small in size and had prominent skeletal deformities and clinical muscle weakness. These features were not present in her brother, suggesting clinical variability. Mental function was normal in both. Bone histology showed osteopenia. Several biochemical events of procollagen biosynthesis were analysed in fibroblast cultures, but no significant abnormalities compared to control fibroblast cultures were detected.