Partial monosomy of 10p is a rare chromosomal abnormality. Common features are hypoparathyroidism, deafness, renal anomalies, distinctive facies, and mental retardation, with phenotypic variability. We report two patients with chromosomal abnormalities identified on single-nucleotide polymorphism (SNP) array analysis. Although patient 1 had common features of monosomy10p, G-banding indicated a normal karyotype. SNP array and fluorescence in situ hybridization (FISH), however, indicated unbalanced translocation of a 10p terminal deletion of 11.7 Mb and a 15q terminal duplication of 8.2 Mb. In patient 2, SNP array and FISH indicated a 10p terminal deletion of 12.6 Mb and a 7q terminal duplication of 1.9 Mb. This is the first case report of monosomy 10p combined with trisomy 15q (patient 1). Because the clinical heterogeneity of the 10p deletion syndrome would be affected by duplication of another chromosome, we emphasize that SNP/microarray analysis is necessary to confirm genotype-phenotype correlation.