T(CD3+)-, B(CD19+)-lymphocytes and their subsets (CD4+, CD8+, CD3+ DR+, CD3- DR+) in peripheral blood of patients with CIN I, CIN II, CIN III and cancer in situ associated with HPV infection were evaluated. In peripheral blood of women with CIN II, CIN III and cancer in situ the number of T-lymphocytes which expressed CD3+ DR+ antigen decreased. In patients with CIN I, CIN III and cancer in situ the level of the CD4+ cells decreased; the level of the CD8+ cells increased. These patients had a lower CD4/CD8 ratio, the number of B cells being standard. The results may have important implications in the prognosis and immunotherapy of HPV infection.