We describe the cytogenetic and molecular characterization of an inverted duplication of chromosome 15q with evidence of a terminal deletion of the same rearranged chromosome. The proband was a multiple congenital malformed female with a prenatal diagnosis of trisomy 15q and an extremely severe clinical course. The phenotype of the patient was characterized by marked intrauterine growth retardation, congenital heart defect, “horseshoe” kidney, hand contractures, and clubfeet. The exitus came at 20 days because of progressive cardio-respiratory impairment. Overall, the clinical phenotype appeared more severe than usual trisomy 15q syndrome. Postnatal cytogenetic and molecular studies unraveled a “de novo” inverted duplication of 15q (q21.3→q26.3), associated with the deletion of the 15q telomere and part of the band 15q26.3. A single copy region spanning approximately 600 kb between the duplicated segments was present. Correlation between the clinical findings of the patient and the phenotype of trisomy 15q reported in literature is also provided. © 2004 Wiley-Liss, Inc.