Studies of normal human lacrimal glands were performed by utilizing fluorescent antibody and ultrastructural techniques in order to examine immunoglobulin production and localization within the gland, and to investigate mechanisms of transport of these immunoglobulins from the gland. Throughout the interstitium of each gland, clusters of cells having the morphologic characteristics of plasma cells were evident. Fluorescent antibody staining showed these cells to contain predominantly IgA, with IgG or IgM occasionally present, and IgE only rarely demonstrable. Extracellular IgA staining was seen along basement membranes of acini, between acinar epithelial cells, and occasionally within acinar lumina. IgA was also occasionally seen intracellularly throughout acinar epithelial cells. IgG was diffusely evident throughout the interstitium but appeared particularly concentrated along the acinar basement membranes. Secretory component and lactoferrin were localized to the acinar epithelial cells, and secretory component could also be found in acinar intercellular spaces. The larger numbers of IgA-containing plasma cells relative to other immunoglobulin-specific plasma cells are consistent with the known proportions of immunoglobulins in tears, and suggest their local production within the lacrimal gland. A secretory mechanism involving intracellular transport of immunoglobulins by acinar epithelial cells is proposed.