Ten cases of the basal cell naevus syndrome (BCNS) are reported. The study is based on clinical findings with no investigations beyond two skull radiographs. The diagnosis is made on some or all of the following findings: family history, jaw cysts, progressive development of basal cell carcinomas (BCCs), pitting of the palms and soles, frontal bossing, abnormality of the skeletal system and ectopic calcification. Eight of the cases are in one family covering three generations. With the exception of a one-year-old child in the third generation (not included) all of this group have the syndrome. The dominant trait is demonstrated, as is the high degree of expressivity and penetrance. Genetic counselling is essential where applicable. Sympathetic regular clinical examination over a lifetime is recommended to avoid disastrous complications.