Background: Severe forms of genital endometriosis are known to be associated with infertility and its subsequent treatment failure. Both gonadotropin-releasing hormone analogs (a-GnRH) and dienogest have been suggested as additional hormone therapy for patients with endometriomas. However, the result of hormonal suppression before an in vitro fertilization (IVF) cycle remains undetermined. Materials and methods: A prospective cohort study of 144 infertile women planning IVF after laparoscopic surgery of ovarian endometriomas was conducted at our department in 2012–2015. Patients were divided into three groups: group I (N = 38) with dienogest course, group II (N = 70) with a-GnRH group III (N = 70) without any hormonal therapy within 6 months preceding IVF. Results: The study groups did not differ by removed endometriomas size and ovarian reserve indicators. The gonadotropin dose per Cycle was higher, while the number of retrieved oocytes was lower in group III patients (p <.001). In women with dienogest pretreatment, clinical pregnancy rate was 2.5 times (44.7% versus 16.7%, p =.012) and delivery rate–three times higher (36.8% versus 11.1%, p =.013) as compared with those from group III. Conclusions: The present study confirms the necessity of pre-cycle medical interventions in women with ovarian forms of endometriosis undergoing IVF. We suggest dienogest to be possibly more efficient treatment option for this kind of patients.