Wolf-Hirschhorn syndrome (WHS) or 4p-deletion syndrome has been extensively described in children. Knowledge on adult WHS patients is still limited due to the small number of published cases. We present 4 adults and review the literature. The phenotype of adult WHS is in general similar to that of childhood WHS. Growth retardation, microcephaly and mental retardation are the rule in both adults and children. Facial dysmorphism also remains similar. The main difference lies in the absence of serious internal (cardiac) abnormalities in adult WHS. Mental retardation ranges from moderate to severe. The nosological overlap between WHS and Pitt-Rogers-Danks syndrome (PRDS) is discussed. More extensive data on adult WHS are needed for appropriate counselling of families with affected young children.