The technique of nucleic acid in situ hybridization is an effective method for identifying the existence and abundance of nucleic acids in tissue sections or cytological preparations. Such a method has the advantage of keeping morphological relationships intact while identifying changes at the molecular level. As a noncoding regulatory RNA, microRNA has been found to intricately control many physiological and pathological conditions. We provide here a representative fluorescence in situ hybridization protocol for microRNA detection, and note commonly used alternatives, and some troubleshooting points. The method described is based on formalin-fixed paraffin-embedded oral cancer tissues but should be broadly applicable to similarly processed tissues of other types of cancer.