The objective of this study was to report two cases of hereditary chromosomal duplications with favorable outcomes. In both cases, conventional karyotyping showed a normal karyotype. However, chromosomal microarray analysis on uncultured amniocytes detected a 3.2 Mb duplication in the region of arr[hg19] 13q12.11q12.12(22,073,046-25,230,759)×3 in case 1 and a 3.1 Mb duplication in the region of arr[hg19] 6q12(65,423,142-68,550,465)×3 in case 2. In both cases, the chromosomal duplication was inherited from a mother who has no symptoms. Both cases resulted in phenotypically normal babies.