Introduction: Psoriasis is a chronic, immune mediated inlammatory skin disease which is characterized by development of scaly plaques, especially on the scalp, elbows, knees and gluteal cleft. Psoriasis develops as a consequence of an inflammation induced keratinocyte hyperproliferation in epithelial layer of the skin and it advances following the tissue infiltration with immune cells in the dermal layers. An important role in the initiation and progression of psoriasis play the cells of adaptive immunity, especially specialized effector T lymphocyte lines that secrete inflammatory cytokines such as IL-17, IL-22, IFNγ nad TNFα. Objectives: To analyze and compare the frequency of CD3+CD4+ lymphocytes in peripheral blood of patients with PV and healthy controls and establish the connection between the frequency of peripheral CD3+CD4+ T-lymphocytes and demographic and clinical features of patients and disease severity. Material and methods: Peripheral blood of 21 PV patients and 22 PV healthy controls has been collected. Peripheral lymphocytes have been isolated by density-gradient centrifugation with Lymphoprep, marked with anti-human CD3ε FITC and CD4 PE-Cy7 monoclonal antibodies, and analyzed on the flow cytometry instrument (FACS Canto II, Becton Dickinson, USA). Relative frequencies of CD3+CD4+ T lymphocytes have been determined by FlowLogic computer software (Inivai Technologies, Australia). Results: Compared to healthy controls, PV patients have had significantly increased relative frequencies of CD3+CD4+ lymphocytes in peripheral blood. Correlation between relative frequencies of peripheral populations of CD3+CD4+ lymphocytes with demographic and clinical features of PV patients has not been established. Conclusion: PV patients have shown significantly increased frequencies of CD3+CD4+ lymphocytes in peripheral blood. Increased number of CD3+CD4+ peripheral lines in psoriasis is not associated with age, gender, serum levels of anti-CMV, anti-HCV and anti-HBs antibodies and disease severity.