MicroRNAs (miRNAs) are small, noncoding RNAs that regulate the expression of target mRNAs. Although thousands of miRNAs have been identified, few have been functionally linked to specific biological pathways. Microarray-based expression analysis is an ideal strategy for identifying candidate miRNAs that correlate with biological pathways and for generating molecular signatures of disease states. This chapter will describe a simple, low-cost microarray platform optimized for miRNA expression analysis.