The present study evaluated the conventional sperm parameters and the seminal concentration of CD45pos cells (pan-leukocyte marker) of infertile patients with idiopathic oligoasthenoteratozoospermia (OAT). The patients were arbitrarily divided into three groups treated with recombinant follicle-stimulating hormone FSH: α (Group A = 20 patients), recombinant FSH- β (Group B = 20 patients), and highly purified human FSH (Group C = 14 patients). All treated groups achieved a similar improvement of the main sperm parameters (density, progressive motility, and morphology), but only the increase in the percentage of spermatozoa with normal morphology was significant compared to the baseline in all three examined groups. Moreover, all groups had a significant reduction of the seminal concentration of CD45pos cells and of the percentage of immature germ cells. Before and after the treatment, the concentration of CD45pos cells showed a positive linear correlation with the percentage of immature germ cells and a negative correlation with the percentage of spermatozoa with regular morphology. These results demonstrate that treatment with FSH is effective in patients with idiopathic OAT and that there are no significant differences between the different preparations. The novelty of this study is in the significant reduction of the concentration of CD45pos cells observed after the treatment.