Forty albino rats, 3-4 months of age, were divided into 4 groups, each consisting of 5 males and 5 females. The animals of groups 1 and 11 had pellets of dimethylbenzanthracene (DMBA) implanted into the right submaxillary gland according to the technic of Cataldo and Shklar. The animals were separated according to sex and fed a standard laboratory diet. Animals of group 1 served as DMBA controls. Two weeks after the start of the experiment, animals of groups 11 and 111 were given daily 0. 5 mg parenteral injections of cortisone acetate. Animals of group 111 served as cortisone controls. Eight weeks after the start of the experiment, half of the animals were sacrificed. The remainder of the animals were sacrificed after 12 weeks. The salivary glands were separated and the pellet of DMBA was removed from the right submaxillary gland of groups 1 and 11 animals. The glands were placed in 10% formalin for 48 hours, sectioned in paraffin at 6 microns and stained with hematoxylin-eosin. Implantation of DMBA pellets into the submaxillary glands resulted in wide variety of cellular alterations ranging from metaplasia to neoplasia. Following initial inflammatory changes, there was the development of epidermoid cysts and the transformation of the cyst epithelium to epidermoid carcinomas. Those animals receiving cortisone developed carcinomas more rapidly and large numbers than the DMBA controls. The difference could not be clearly discerned at 8 weeks, but at 12 weeks the DMBA-cortisone group had developed frank malignancies in 6 animals while the DMBA controls had developed 1 malignancy. Furthermore, the development of dys-keratotic alterations was more pronounced in the DMBA-cortisone group.