To find immunomorphologic evidence of interregulation between neuroendocrine system and immune system by detecting 5-HT in human normal lymph-node and lymphoma.Methods:Immunohistochemical SABC method and statistics analysis.Results:Thirty-three cases of lymph-nodes showd 5-HT positive expression.The positive rate of lymphoma is lower than that of normal lymph-node.The differences between human normal lymph-nodes and lymphoma are significant( P