This is a clinical and roentgenological report on the treatment of two infants with osteogenesis imperfecta with sodium fluoride. The drug was administered orally, and treatment has continued over a period of four to nine months with good clinical and roentgenological response. There have been no toxic reactions to the drug, and no reports of additional fractures since treatment was started. Both patients were given 15 to 30 mg fluoride per day (or three to six mg sodium fluoride per kg per day). No data on calcium retention during fluoride treatment was obtained.