ABSTRACT: Chromosomal imbalances are implicated in the etiology of developmental delay (DD) and congenital malformation (CM). We therefore conducted high resolution array comparative genomic hybridization (array CGH) of sixty three Saudi patients [11 by Agilent-001850/CGH1x244A and 52 by Agilent-014693/CGH2x400k] for investigating and understanding the genetic heterogeneity underlying DD/CM. A total of 76 disease associated copy number variants (CNVs) were detected in twenty four patients including 1p36, 1q21, 3p23, 6p24, 7q11, 8q24, 9q33, 10p14, 11p15, 11q12, 11q24, 13q21, 15q13, 16p13, 18q23, trisomy 18, 20q11, 21q22, 22q11.21, 47,XXY and 45,X0. The diagnosis rate of array CGH was 2.6 times higher than karyotyping.