The aim of the study was to evaluate FoxP3+ regulatory T cell (Тreg) subsets in the follicular fluid (FF) of the women undergoing in vitro fertilization (IVF), and their relationships with features of folliculogenesis and oogenesis, as well as quality of embryos and retrospective assessment of IVF outcomes. The study included 53 women at the age of 25 to 46 years stimulated by superovulation. The count of Tregs in the FF samples was determined by flow cytometry using appropriate monoclonal antibodies. The FF examination revealed of FoxP3+ T cells from both CD4+ (CD4+FoxP3+) and CD4- (CD4-FoxP3+) T lymphocyte subsets. Moreover, the FoxP3+ cells were registered in CD4+CD25+ and CD4+CD25- T lymphocyte subsets. Follicular fluid of women with a relatively small number of follicles contained higher numbers of CD4+CD25-FoxP3+ T cells, whereas a reduced number of oocytes was associated with the highest count of CD4-FoxP3+ T cells in FF. Retrospective analysis showed the a relationship between percentage of Tregs, and quality of oocytes and embryos. High fertilization index (0.75-1.0), reflecting maturity of the oocytes was associated with higher count of CD4-FoxP3+ T cells in the FF. Better quality of blastocysts was associated with a higher count of both CD4-FoxP3+ and CD4+FoxP3+ T cells. Onset and progression of pregnancies was also registered in women with relatively high counts of CD4-FoxP3+ T cells. The obtained data showed presence of different FoxP3+ T cell subtypes in follicular fluid, and its possible role in controlling early stages of reproductive process. CD4-FoxP3+ T cells seem to be the most important subpopulation; their counts are associated with efficacy of oogenesis, blastulation and pregnancy occurence.