IHC antigen retrieval is used to reverse fixation-related epitope masking and improve antibody access in immunohistochemistry. Because formaldehyde-based fixation can create protein cross-links that weaken or prevent staining, antigen retrieval is often needed before antibody incubation. In this video, we explain the main antigen retrieval methods, including heat-induced epitope retrieval (HIER) and proteolytic-induced epitope retrieval (PIER), and share tips for selecting the right conditions for your tissue and antibody.