Thirteen cases of nasopharyngeal carcinoma (NPC) and 16 cases of non-NPC tumors in the nasopharynx or in adjacent locations were investigated clinically, immunologically, and pathologically. All tumors were classified according to the TNM classification, and the stage and course of the disease was correlated with the histological tumor type, the T- and B-cell distribution in tumor tissue and in the peripheral blood, as well as with antibody titers against Epstein-Barr virus (EBV). The results showed a positive correlation of decreased T- and B-cells in tumor tissue and of decreased T-cells in the peripheral blood with the extend of the tumor in both NPC and non-NPC cases, with some exceptions of lymphocyte rich neoplasms (lymphoepithelial carcinoma and malignant lymphoma). Antibodies against EBV (early antigen and capsid antigen) became progressively elevated with increasing tumor stage in NPC-cases but not in non-NPC cases. The latter, however, was observed only in two histological types of NPC's: anaplastic carcinoma and lymphoepithelial carcinoma; titers in the remaining tumor types stayed insignificant.