We describe an apparent de novo duplication of bands 17p11.2 and p12. A comparison of the manifestations of a previously reported case with a similar karyotype [Magenis et al., Am J Med Genet 24:415-420 (1986)] and of our own case seems to indicate a characteristic pattern which includes prenatal and postnatal growth retardation, facial changes, club feet, and mild developmental deficits. The prominent facial changes are a relatively triangular face, downslanted palpebral fissures, malocclusion, and abnormal ears. In addition, this condition appears to be milder than other duplications of the short arm of chromosome 17, namely trisomy 17p and dup(17)(p11.2----cen).