Immunoprecipitation is the preferred technique used to isolate a specific antigen from a mixture, using the antigen-antibody interaction. The process involves precipitating a protein antigen out of a solution using a specific antibody that binds to that particular protein or biomolecule.

Immunoprecipitation is used to for the purpose of isolating and concentrating specific proteins of interest from samples that contain thousands of different proteins. The isolated protein may then be used in other assay techniques.

There are several variations of the basic immunoprecipitation technique including Co-Immunoprecipitation (Co-IP), Chromatin Immunoprecipitation (ChIP), and RNA Immunoprecipitation (RIP), each of which is used for different purposes