Lymphadenectomy of the regional lymph nodes of the rat liver resulted in the direct influx of peripheral hepatic lymph into the thoracic duct after regeneration of lymphatic vessels. Thus, we could obtain the dendritic cells in the hepatic lymph by cannulating the thoracic duct. By the double immunostaining, dendritic cells in cytosmears could be easily determined as non-B, non-T, and MHC class II-positive cells. The yield of dendritic cells after enrichment by the metrizamide density gradient was about 5 x 10(5)/first 16 hr collection/rat, with viability of more than 95% and purity of more than 70%. About 80% of dendritic cells were positive for OX62, which recognized the rat dendritic cell subpopulation. They showed strong stimulating activity in the primary allogeneic mixed leukocyte reaction. The method presented here should be applicable to studies of the roles of liver dendritic cells, especially in transplantation immunity.