Fibrous dysplasia is a rare genetic bone disorder with a wide variation in clinical expression, ranging from asymptomatic patients to severely affected patients with extensive bone disease, pain, repetitive fractures and deformities and serious endocrinological symptoms (McCune-Albright syndrome). Here, we report on three different cases of fibrous dysplasia. First, a 46-year-old woman with a small solitary lesion in the proximal femur. Second, a 25-year-old man with polyostotic disease of the left leg who received both surgical and medical treatment. Third, a 7-year-old girl with McCune-Albright syndrome who was diagnosed with precocious puberty as a baby and who had extensive disease throughout the skeleton, including multiple lesions in the craniofacial region. The aetiology, clinical expression, diagnostic work-up and therapeutic options for fibrous dysplasia are discussed in a short résumé of the disease.