A de novo interstitial duplication of the 6q11-q15 chromosome region, confirmed by the application of a chromosome 6 painting probe, was observed in a patient with craniofacial dysmorphism, psychomotor retardation, cryptorchidism and hypospadias. Despite the publication of several cases showing partial trisomy 6q, to our knowledge the duplication of the proximal region q11-q15 has not previously been reported.