Regulatory T cells (Treg) are important regulators of anti-cancer immune responses, and an increase in Treg frequency was observed in the blood of cancer patients. Blood samples from 112 patients with head and neck squamous cell carcinoma antigen (HNSCC) were obtained at the time of tumour diagnosis, and lymphocyte subpopulations (CD3(+); CD3(-)CD16(+)CD56(+); CD4(+); CD8(+); CD19(+); CD4(+)CD45RA(+)) with emphasis on Treg counts (CD3(+)CD4(+)CD25(+)), complete blood count and tumour markers (squamous cell carcinoma [SCC]; CEA; alpha-1-antitrypsin [AAT]; Cyfra 21-1; C-reactive protein [CRP]) were analysed. The data were grouped according to TNM classification, and their significance for the course of the disease at an interval of 1 year after the end of the therapy was determined. The percentage of CD8(+) cells increased and the CD/D8 ratio decreased with tumour grade. The ratio of B lymphocytes decreased in patients with locoregional metastases (11.25%versus 9.22%). Treg (15.2%) and CD4(+) cells (45.3%) increased, while NK cells (11.8%) decreased in HNSCC patients compared to controls (9.0%, 38.1% and 15.8%, respectively). The data obtained at time of diagnosis were used to assess the significance of tumour markers (SCC, Cyfra 21-1 and AAT) for evaluation of prognosis. The erythrocyte counts (4.64 x 10(12)/l versus 4.45 x 10(12)/l) and haemoglobin levels (14.58 g/dl versus 14.05 g/dl) decreased, while Treg counts (8.91%versus 15.70%) increased in patients with early recurrence. Our results show that examination of these parameters could be helpful for prognostication in HNSCC patients and aid improvement of treatment strategy.