IgA-, IgG, and IgM-producing plasma cells as well as 3- and T-lymphocytes were immunophenotyped and quantitated in a series of 216 benign and malignant salivary gland tumors, with special emphasis placed on the clinical behavior of the tumors. Highest number of plasma cells were found in mucoepidermoid carcinomas, where IgG-plasma cells were the sole Ig-class secreted. No IgA-immunoreactivity was found in adenoid cystic, undifferentiated, acinic cell, carcinoma in pleomorphic adenoma, and mucoepidermoid carcinomas. In squamous cell carcinomas, the number of IgM-plasma cells was higher than that in other salivary gland tumors. Basal cell adenomas contained only IgM-positive plasma cells. In logistic regression analysis, IgG- and IgM-producing plasma cells in malignant salivary gland tumors were related to an increased tumor diameter (p = 0.022 and 0.046, respectively). In benign tumors, neither clinical nor prognostic value could be attributed to the distribution of plasma cells. T-cells and B-cells were present in 63.9% and 33.8% of all tumors, found in 63.8% and 26.7% (p = 0.0048) of the benign tumors, and in 64.1% and 41.7% (not significant) of the malignant tumors, respectively. The presence of T- of B-lymphocytes was of no prognostic significance in malignant tumors. In benign tumors, however, the mean age of the patients was significantly higher (p = 0.010) and the mean time to recurrence significantly shorter (p = 0.018) in patients with tumors containing T-cells than in those devoid of these cells. In conclusion, the cell-mediated immunity (T-cells and their subsets) seems to play a more important role in pathogenesis and prognostication of salivary gland neoplasms than do the cells of the B-cell lineage, and, clearly, further studies are needed to elucidate these issues.