We describe a family with two marriages of first cousins and a total of five children with opsismodysplasia. The diagnosis was based on clinical, radiological, and immunhistochemical findings. Helpful to the diagnosis was the testing with type I collagen antibodies, showing abnormally high levels in the hypertrophic area of growth cartilage. This observation supports the hypothesis of autosomal recessive transmission of opsismodysplasia.