Immunohistochemistry is the process of detection of antigens in tissue using antibodies. The antibodies can be polyclonal or monoclonal in origin, the monoclonal ones being more specific in nature. Immunohistochemistry is widely used for diagnosis of cancers. Specific markers are known for various cancers.

• Carcino-embryonic antigen (CEA): used for colon cancer
• CD15 and CD30 : used for Hodgkin's disease
• Alpha fetoprotein: for yolk sac tumors and hepatocellular carcinoma
• CD117: for gastrointestinal stromal tumors (GIST)