Epidemiologic data on 45 patients with Rubinstein‐Taybi syndrome from the Netherlands and 50 patients from the USA are compared with data from 407 patients reported in the literature. The 502 probands had a total of 708 sibs, including one probable recurrence. In 12 of 13 proven or possible monozygotic twins both children were affected. Two patients have reproduced with one affected and 2 normal offspring. The empiric recurrence risk figure for sibs is 0.1%. The recurrence risk for offspring of affected individuals could be as high as 50%. The cause of the syndrome remains unknown. There were no clues for autosomal recessive or X‐linked inheritance, nor for a teratogenic cause. No consistent chromosome anomaly was found. An autosomal dominant mutation, either as submicroscopic chromosome deletion or duplication, or a point mutation seems the most likely explanation.