Carcinogens injected into the excretory canal of submandibular gland of Donryu rats revealed the following histologic changes in salivary glands. 20-Methylcholanthrene induced squamous cell metaplasia, fibrosis in the early stages, and "benign lymphoepithelial lesion"-like pattern after 3 months. Dense hyalinization occurred after 4-5 months with so-called "mixed tumor"-like pattern. In the later stages epidermoid carcinoma and fibrosarcoma were observed. 9, 10-Dimethylbenzanthracene caused degenerative change, metaplasia, fibrosis and cell infiltration, and later carcinoma and sarcoma appeared at a high rate. 4-Nitroquinoline-N-oxide led to dense hyalinization and so-called "mixed tumor"-like pattern was observed in many specimens. N-nitroso-N-methyl urethane and N-methyl-N-nitroso-N'-nitroguanidine revealed metaplastic changes, fibrosis and lymphoid infiltration. Scarlet red induced remarkable infiltration and aggregation of lymphoid cells, showing benign "lymphoepithelial lesion"-like pattern.