Stimulation of cell-mediated immunity (CMI) by 2,4 dinitrochlorobenzene (DNCB) was reported to be effective in clinical regression of some carcinomas and precancerous lesions. This study investigated development of CMI in rat submaxillary salivary glands with dermal application of DNCB to provide a model for the study of immunotherapy in salivary gland neoplasia. Twenty rats received 0.02 ml of 0.5% DNCB in 4:1 acetone corn-oil applied with a glass rod to 3 cm2 of clipped ventral skin of the neck covering the submaxillary salivary gland on 2 successive days. Ten days later, the submaxillary glands were challenged with an injection of 0.02 ml of DNCB. Thirty-two h later the animals were killed and the glands examined grossly and microscopically. Thirty control animals were sensitized and challenged, (a) 10 with 0.5% DNCB, then vehicle only, (b) 10 with vehicle only, then 0.5% DNCB, and (c) 10 with vehicle both times. Gross examination of experimental and control glands disclosed moderate edema and congestion. Microscopically, experimental glands showed inflammatory changes including infiltration, vascular congestion and perivascular cuffing of lymphocytes. Regional lymph nodes showed proliferation of cortical germinal centers only. Control glands showed acute vascular congestion in group (a), and absence of microscopic features of delayed hypersensitivity.