The localization of immunoglobulins IgA, IgG and IgM in porcine intestinal tissue by immunofluorescence is described and the influence of three fixatives, ethanol, methanol and acetone on the findings compared. Methanol was found to be the only fixative to give consistent results for IgM; it was also the reagent of choice for the localization of IgA in cells of the lamina propria. However ethanol and acetone were preferred for the demonstration of secretory IgA. Extravascular IgG was shown to be still soluble after fixation and capable of being removed from the tissue. The demonstration of IgM in intestinal crypt epithelium is reported and its possible role as a secretory antibody acting in concert with IgA is discussed.