We studied the lymphocyte subpopulations T4+ and T8+ through monoclonal antibodies (McAb). The end of our study was focused in understanding the differences between the values mentioned by the literature and, consequently, determining our range of normality. Thus, we determined the subpopulations T4 and T8 using the antibodies OKT4 IND and OKT8 SUP, which define respectively the subpopulations T helper and T suppressor. Such determinations have been fulfilled whether on the total lymphocytes or on the lymphocytes T purified. Of course, the results obtained are different if we use the total lymphocytes or lymphocytes T purified. This confirms our suspect that the different values mentioned by the literature are determined by the two possible methods: T purified or total lymphocytes. In order to avoid interpretative mistakes, we suggest to express the values of T4+ and T8+ through the relation T4/T8; in fact, studying the single values obtained by the two different methods we proved they are different, but, at the same time, the relation T4/T8 remain unchanged in each method and is included in a "range of normality" from 1,4 to 1,7.