Array comparative genomic hybridization (aCGH) takes the concept of CGH and moves it onto the high throughput medium of a glass slide. It utilizes specific, immobilized probes that can be interrogated using DNA from normal and diseased sources, providing a wealth of information on copy number changes throughout the genome at much finer resolution than has been previously achievable. Apart from its research applications, aCGH is well on its way to becoming a standard clinical diagnostic tool. With the rising interest in tailoring diagnosis, therapy, and outcome prediction to the individual—commonly known as personalized medicine—there is an increasing demand for such technologies. As the line between laboratory and bedside blurs, the translation of research methodologies into a clinical setting clearly points to a future where those technologies currently driving discovery will also provide robust tools for molecular diagnostics.