During a systematic chromosomal survey of 7 unrelated patients with Rubinstein-Taybi syndrome, an apparently balanced de novo reciprocal translocation, t(7;16)(q34;p13.3), was detected in an affected boy. The involvement of the region 16p13.3 coincides with the position of one of the breakpoints in another de novo reciprocal translocation associated with Rubinstein-Taybi syndrome, suggesting that a locus for this syndrome maps to 16p13.3.