The mechanisms of endometriosis-related infertility remain still unknown. Endometriosis and clinical markers of oocyte quality are a very important problem of reproduction. The purpose of the study is to assess the quality of oocytes in women with infertility associated with endometriosis. The study included infertile reproductive aged women, between 29 and 40 years who underwent IVF and ICSI procedures. The patients were divided into three groups: group I involved 50 (n = 50) patients with recurrent unilateral endometriomas, group II included 50 patients (n = 50) unilateral endometriomas after surgical treatment and control group with 30 (n = 30) patients with tubal factor infertility. Clinical and morphological assessment of oocyte quality was performed in all IVF/ICSI cycles. The results of the study demonstrate a statistically significant increase in the number of immature oocytes of metaphase MI and immature oocytes at the GV germinal vesicle stage in patients with infertility associated with endometriosis, compared with the control group (p<.005). There is deterioration in the quality of the obtained oocytes in patients with the presence of endometrioma more than 3 cm in diameter. The results of this study allow to conclude that endometriomas negatively affect quality of oocyte and ovarian reserve, whereas endometriomas after cystectomy, have a deleterious and sustained effect on ovarian reserve. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.