Immunohistochemistry is used on cell blocks constructed from cytopathology samples fixed in methanol-based fixatives, such as CytoLyt® (Cytyc Corp), and on surgical pathology tissues exposed to decalcifying agents, often without technical validation. We evaluated a panel of commonly utilized antibodies in normal tissues exposed to differing preanalytic conditions as follows: CytoLyt® fixation, formalin fixation followed by exposure to decalcifying agents (Leica Decalcifier I-10% formic acid or Leica Decalcifier II-5% hydrochloric acid), or standard formalin fixation. Altered expression was observed with several antibodies compared with standard formalin fixation. Specifically, there was absent or near absent expression of thyroid transcription factor 1 (TTF-1), D2-40, and CD20 in CytoLyt-fixed tissues, whereas reduced expression was observed for p63, estrogen receptor, S100 protein, CD3, calretinin, chromogranin, and synaptophysin. Absent or near absent expression of TTF-1 was also observed with exposure to hydrochloric acid, whereas reduced expression was observed for CK5/6, CK7, p63, estrogen receptor, leukocyte common antigen, CD3, CD20, and synaptophysin. Exposure to formic acid had less impact with reduced expression observed for only 3 antibodies (CK8/18, CK7, and TTF-1). The results of this study demonstrate the need to validate immunohistochemical protocols on control tissue treated in the same manner as test tissue, including CytoLyt® fixation and exposure of tissue to decalcifying agents.