This report describes the dental findings and management of siblings in a family in which three generations had been affected by osteogenesis imperfecta Type IV with opalescent dentine. Hereditary opalescent dentine, or opalescent teeth, is a pathologic dental condition characterised by a disturbance of dentine formation that occurs concurrently with osteogenesis imperfecta. Osteogenesis imperfecta is a genetically heterogenous group of systemic disorders of the connective tissue. The two siblings affected with opalescent dentine were treated under general anaesthesia, and included stainless steel crowns, extractions, and strip crowns on primary teeth. These reports highlight that appropriate treatment of the dentition of young patients with opalescent dentine should be carried out early in the primary dentition, and that this initial treatment can have long-term benefits in the mixed and permanent dentitions.