Fibrous dysplasia is a rare bone disease caused by an abnormal proliferation of fibrous tissue in bone. We retrospectively evaluated eight patients (female to male ratio 3:1, mean age 22.5 years, range 10-32) with a monostotic form who were treated between 1996 and 2006. Two each were affected in the lower jaw, the upper jaw, the midface, and the frontoparietal region. Most patients were referred because of a painless swelling. Biopsy specimens from two patients were examined, six patients had modelling osteotomies, two of whom had further operations because of progressive enlargement. There was no visual impairment or malignant transformation. Fibrous dysplasia should be treated as conservatively as possible, but in cases of functional disturbance that results from malignant transformation, or from the involvement of the optic foramen or the foramen magnum, an immediate operation is needed. Disfigurement can be another reason for operation. When there is a risk of malignant transformation, follow-up of patients is recommended.