We report on two families with different expression of a Van-der-Woude-Syndrome (VWS) and with proven mutation of the IRF6- gene. The Van-der-Woude syndrome is a rare disease, typically consisting of congenital pits of the lower lip in combination with cleft lip or cleft palate or both. The Van-der-Woude syndrome is an autosomal dominant syndrome with variable expression. The penetrance is between 0,89 and 0,99. It is important to establish the correct diagnosis by careful investigation of patients with cleft lip or cleft palate and their parents. Genetic counselling is recommended in such cases.