Constitutional chromosomal imbalance has been recognized, for a long time, as an important cause of congenital and developmental abnormalities including developmental delay (DD), intellectual disability (ID), autism spectrum disorders (ASD) and/or multiple congenital anomalies (MCA). The high-resolution array-based comparative genome hybridization (array CGH) has led to the detection of large numbers of copy number variants (CNVs) in patients with developmental delay and/or multiple congenital anomalies, as well as in healthy individuals, that challenges the interpretation of the clinical significance of detected CNVs in patients. The objective of this work is to present a retrospective review of array-CGH data of 482 children with unexplained intellectual disability +/- congenital abnormalities. This work reinforces the current status practice of array-based technology use for postnatal diagnosis and supports that it will replace standard cytogenetics as a first-line test for clinical evaluation in the population with ID +/- congenital abnormalities.