Rare disorders are conditions defined as either fatal or causing chronic functional impairment. There is limited evidence of the behavior of oral implants in patients suffering from such diseases, and the existing data are merely based on cases reports. This paper describes the outcome of implant treatment after up to 15 years of function in three patients afflicted with X-linked hypophosphatemia, two patients with Langerhans cell histiocytosis, and one patient with osteogenesis/dentinogenesis imperfecta.