The use of microarray technology in chronic myeloid leukaemia (CML) has increased our understanding of the biology of this disease. From early studies of gene expression profiling in BCR-ABL-positive cell lines to samples from patients in different disease phases of CML, using resting cells or cells treated with a variety of therapeutic agents, the field has now moved on to profiling microRNA and single nucleotide polymorphisms of CML cells. With the advent of tyrosine kinase inhibitors, several groups have also attempted to use microarray profiling to ascertain if particular gene expression profiles pre-existing in patients' CML cells, which could reflect intrinsic disease biology, would predict for response to treatment. This could streamline patients for alternative treatments upfront should a poor risk profile be found. In this article, we provide an overview of the progress made so far in this field, and outline the more substantial results of available microarray studies to date.