A trisomy 17pter --> p11.2 derived from a supernumerary de novo satellited marker was identified by GTG bands and fluorescent in situ hybridisation (FISH) in amniocytes of a fetus with malformations and intrauterine growth retardation (IUGR). At 39 weeks a male infant with a phenotype similar to other postnatal cases of 'pure' complete trisomy 17p was born. Some additional clinical features, however, make him more severely affected than previous patients.