he purpose of this study was to evaluate the prognostic influence of various subtypes of tumour infiltrating lymphocytes (TIL) in head and neck cancer, in particular the potential influence of regulatory T cells (Treg) in relation to different treatment modalities was addressed. A total of 115 patients with squamous cell carcinoma of the oro- and hypopharynx were selected. A low-risk group of 62 patients with early disease was treated by primary surgery followed by external radiotherapy. A high-risk group of 53 inoperable patients with advanced disease was treated by primary radiochemotherapy. Two-hundred and forty biopsy samples were evaluated by use of the tissue-micro-array technique employing the following markers: CD3, CD4, CD8, CD20, CD68, FOXP3, Granzyme B. In the low-risk group high CD20+ infiltration was associated with a significantly better NED-survival rate (p=0.02). Contrary, among high-risk patients low CD20+ counts indicated significantly better survival (p=0.03). Additionally, in the low-risk group higher numbers of intraepithelial CD8+ TIL (>66.6 per thousand) led to improved NED-survival of 95% vs. 52% (p=0.005). The impact of TIL on prognosis in patients with head and neck cancer may be affected by type of treatment and stage of disease. This finding will influence future studies on the role of TIL in human cancers.