Presentation is made of 2 boys and a girl with fibrous dysplasia involving the frontal and ethmoidal sinuses and the maxilla. This tumor-like growth of the bone was not restricted to the sinus alone but expanded to the orbit, adjacent sinus, skull base and infratemporal or pterygoid fossa. In such cases, surgical therapy is the treatment of choice, with maximal preservation of healthy tissue and avoidance of major devastations that may result in undesired cosmetic defects. The etiology of the disease is still unknown. However, it should be emphasized that all 3 patients had suffered an injury to the adjacent bony structures at various time points preceding the disease manifestation. That is why we are inclined to believe that trauma might be a factor responsible for the onset of fibrous dysplasia.