Differential display and other techniques such as subtractive library screening and representational difference analysis have been developed and widely used for novel gene discovery in pathological and specific physiological conditions. In the present work, we illustrate the utilization of the differential display method for the investigation of the differentially expressed genes in a rat model of focal brain ischemia. Adrenomedullin, a recently discovered vasodilator peptide, was identified to be upregulated after focal brain ischemia and further demonstrated to play a pathophysiological role in exacerbating ischemic damage. The data suggest a high potential for the application of mRNA differential display, as well as other techniques, for the discovery of novel therapeutic targets.