We characterized the inflammatory infiltrate of two sebaceous cell carcinomas of the eyelid with immunohistochemical staining to determine the functional class of the mononuclear cells associated with the tumor. The results were compared with the inflammatory infiltrate associated with basal cell carcinomas. The subepithelial spaces and the area immediately surrounding the sebaceous cell neoplasms were free of mononuclear inflammatory cells, in contrast to the basal cell tumors, which had large numbers of subepithelial inflammatory cells and inflammatory cells in intimate contact with the neoplastic cells as previously reported. Inflammatory reaction in the sebaceous cell tumor was limited to a T-cell infiltrate surrounding the vessels adjacent to the tumor. The predominant mononuclear inflammatory cell in both the sebaceous cell and the basal cell carcinomas was the T helper cell. The apparent difference in mononuclear cell infiltrate may be a significant factor in the clinical behavior of the tumors.