Protocol details the preparation of fluorescently labeled target samples and hybridization of these samples to a microarray of Agilent inkjet-deposited presynthesized oligonucleotides. The procedure requires a minimum of 3 µg of purified total RNA as starting material. Includes: cDNA Synthesis; Fluorescent cRNA Synthesis; cRNA Precipitation and Cleanup; cRNA Quantification; Hybridization; Washing.