hemagglutination inhibition (HI), 1. the inhibition of virus-induced hemagglutination as a procedure for identifying hemagglutinating viruses. HI is used in the diagnosis of infections by certain viruses, such as rubella, herpes zoster, and herpes simplex. 2. a method for measuring the concentration of soluble antigens in biological specimens in which the specimen is incubated first with homologous antibodies and then with antigen-coated erythrocytes.
