In 1984, 32 persons with Laurence-Moon-Bardet-Biedl syndrome (LMBB) were registered in Norway. This means that the disorder was seen at a rate of 1 in 128,000 inhabitants. Of these, 26 attended the Frambu Health Centre, where they consulted a pediatrician, a psychologist, a dentist, a social worker, a geneticist, a teacher for the blind and an ophthalmologist. The cardinal signs were retinitis pigmentosa, obesity and polydactyly. We also found that all the patients had disturbance of tooth formation. Many had hypogenitalism. Mental retardation is usually included as a cardinal sign. Our impression is that most of the patients have normal intelligence. But this will be investigated further in a follow-up study on young people with LMBB.