Partial trisomy of the long arm of chromosome 19 is a rare aneusomy. Only six cases of pure duplications have been previously reported, two of which were prenatally detected. Here we describe the clinical manifestations in a 15-month-old girl with a de novo dup(19)(q12q13.2) and the application of array-based comparative genomic hybridization with a resolution of approximately 1 Mb to characterize the duplicated segment. Seven clones were found duplicated, and the size of the fragment was determined to be 10.8 Mb. The scarce number of patients reported and the difficulty of accurately defining the duplicated segment when conventional cytogenetic methods are applied hamper the delineation of a clinical phenotype for duplication of chromosome 19q. To our knowledge this is the fifth live born reported with a pure dup(19), and the first report in which the duplicated segment has been accurately characterized by means of array CGH.