Abstract: DADL,a-δreceptor selective enkephalin analogue , was prepared with the technique of solid-phase peptide synthesis. It was found to stimulate directly the proliferation of mouse splenic lymphocytes dose-dependently. However , synergistic effect of DADL at different concentrations with ConA and LPS were not found. In addition, TNF-a production was increased by ip DADL(1. 0 mg· kg^-1X6d)in mice and the production of LPS-induced TNF-a in mouse peritoneal macrophages was enhanced after DADL was added in vitro. These esults suggest that DADL , like enkephalins , exerts some immunoregulatory activities.