A case of hyperplastic callus formation is reported in a girl of eleven; several bones were affected. There were no associated fractures. She is believed to be suffering from a mild non-familial type of osteogenesis imperfecta without blue sclerotics and presents multiple bony excrescences unassociated with injury. The relevant literature is reviewed. The effect of a trial of treatment with A.C.T.H. and with deep x-ray is reported.