A very early case of infantile cortical hyperplasia (Caffey disease) is reported. The ultrasound examination performed at 22 weeks gestational age evidenced angulations of the long bones, leading to the diagnosis of lethal osteogenesis imperfecta. Hydrops fetalis developed and the pregnancy was terminated. The roentgenographic study of the fetus and results of pathological studies led to the correct diagnosis of Caffey disease. The difficulty of the diagnosis of these early forms of infantile cortical hyperostosis should be pointed out.