Three unrelated patients with congenital arthrogryposis and brittle bones, the main neonatal signs of Bruck syndrome, are presented. In infancy and early childhood recurrent fractures of ribs and long bones and persistent Wormian bones in the calvarium are reminiscent of osteogenesis imperfecta (OI) even with white sclerae, normal dental quality and normal hearing as important clinical negatives. The diagnosis was made before two years of age in two, and in adolescence in the third patient. The latter's radiologically documented long-term natural course reveals slow progressivity of osteopenia and growth deficiency, worsening tendon contractures and pterygia in addition to increasing spine and pelvis deformation. Mental development remains normal. Bruck syndrome is monogenic and probably due to homozygosity of an as yet unidentified gene. As no alteration in the collagens I and III is detected and molecular screening reveals no mutation in the COL1A1 and COL1A2 genes, the pathogenesis of this severe disorder of connective tissue remains largely unknown.