Infantile cortical hyperostosis - Caffey-Silverman disease - is a familial disorder manifesting in the late fetal period or infancy with excessive periosteal bone formation. Signs and symptoms regress spontaneously within months and result in expanded, deformed bones. The paucity of clinical symptoms may lead to delayed investigation and confusion of the remaining bone changes with those in other conditions. This problem is exemplified by two siblings misdiagnosed as osteogenesis imperfecta. The diagnosis of Caffey-Silverman disease was confirmed by molecular analysis showing the specific COL1A1 mutation in the patients and their clinically unaffected mother. Reduced penetrance rather than autosomal recessive inheritance explains multiple affected siblings born to healthy parents.