In situ hybridization (ISH) has significantly advanced the study of gene structure and expression in cells and tissues, but its application is often limited by detection sensitivity. The introduction of signal amplification after ISH using tyramides has greatly advanced in situ detection methods that also are now applicable in routine diagnostics. In this chapter, we provide detailed step-by-step protocols for synthesis of biotinylated tyramides, multiple-target deoxyribonucleic acid-ISH on cell preparations, both DNA- and messenger ribonucleic acid (mRNA)-ISH on formalin-fixed, paraffin-embedded tissue sections, and tyramide signal amplification for signal detection.