27 cord blood samples from healthy newborns were processed according to a "whole blood" flow cytometric analysis. The CD3-positive T cells are characterized by their variability: 44.8 +/- 13.3% of lymphocytes with a lower expression of the gamma delta T cell receptor. The majority of the CD3+ cells are CD38+. Newborn T cells have less ability than adult T cells to express IL-2 receptors as well as HLA-DR. The CD4-positive T cells are equal to 31.0 +/- 10.8% of lymphocytes with a great prevalence of the CD4+/CD45RA+ population. The CD3+/CD8+/CD11b+ cells are increased to 23.4 +/- 7.1% of lymphocytes. The CD57 antigen is not expressed. The NK population, CD16+/CD56+ is increased to 25 +/- 11% of lymphocytes. 68% of CD19+ cord blood B lymphocytes coexpressed CD5. Thus the "suppressive" and "naïve" cells are prominently represented in cord blood.