Objective: Poor responders are often associated with a large consumption of gonadotrophins with a partial or complete lack of ovarian response, irrespective of stimulation protocol is used. The aim of this study is to assess the natural cycle in low responders women as an alternative treatment to the oocyte donation.Design: Twenty five poor responders to gonadotrophins underwent 62 natural cycles. We define poor responders as those who produce less than three follicles despite adequate ovarian stimulation.Materials/Methods: When the follicle size was >14 mm, the patient was asked to perform a test for urinary detection of the LH every 6 hours. In the case of spontaneous LH surge, oocyte retrieval was scheduled 30 hours after the observation of a positive coloration with urinary testing. The patients were divided according to the age (<35, 35–40 and >40 years old) and basal FSH levels (<10, 10–15 and >15 UI/L).Results: The mean age was 38 years old (range 33–47). Cancellation occurred in 41 cycles (66%): 5 (12.2%) inadequate follicular growth, 21 (51.2%) spontaneous ovulation, 2 (4.9%) unrecovery oocyte and 13 (31.7%) fertilization failure. 36 (58%) oocyte punctures were performed and oocyte recovery rate was 34/36 (94.4%). Fertilization rate was 68,7%, with embryo transfer in 21 patients (34%). Four clinical and one biochemical pregnancies were obtained, giving a pregnancy rate of 6,4% per cycle, 16% per patient, 11,1% per oocyte retrieval et 19% per transfer. No significant differences were found in cancellation rate with regard to age or basal FSH levels but there were in pregnancy rate per transfer in younger women (<35 = 2/4 (50%), 35–40 = 2/13 (15,3%) and >40 = 0/4 (0%)), and women with lower FSH levels (<10 = 1/2 (50%), 10–15 = 0/5 (0%) and >15 = 2/8 (25%)).Conclusions: Natural cycle would be the best alternative treatment to the oocyte donation in poor responders. The only disadvantage is the low pregnancy rate per cycle due to a high cancellation rate. This could be improved with more strict control in these unstimulated cycles.Supported by: IVI. Objective: Poor responders are often associated with a large consumption of gonadotrophins with a partial or complete lack of ovarian response, irrespective of stimulation protocol is used. The aim of this study is to assess the natural cycle in low responders women as an alternative treatment to the oocyte donation. Design: Twenty five poor responders to gonadotrophins underwent 62 natural cycles. We define poor responders as those who produce less than three follicles despite adequate ovarian stimulation. Materials/Methods: When the follicle size was >14 mm, the patient was asked to perform a test for urinary detection of the LH every 6 hours. In the case of spontaneous LH surge, oocyte retrieval was scheduled 30 hours after the observation of a positive coloration with urinary testing. The patients were divided according to the age (<35, 35–40 and >40 years old) and basal FSH levels (<10, 10–15 and >15 UI/L). Results: The mean age was 38 years old (range 33–47). Cancellation occurred in 41 cycles (66%): 5 (12.2%) inadequate follicular growth, 21 (51.2%) spontaneous ovulation, 2 (4.9%) unrecovery oocyte and 13 (31.7%) fertilization failure. 36 (58%) oocyte punctures were performed and oocyte recovery rate was 34/36 (94.4%). Fertilization rate was 68,7%, with embryo transfer in 21 patients (34%). Four clinical and one biochemical pregnancies were obtained, giving a pregnancy rate of 6,4% per cycle, 16% per patient, 11,1% per oocyte retrieval et 19% per transfer. No significant differences were found in cancellation rate with regard to age or basal FSH levels but there were in pregnancy rate per transfer in younger women (<35 = 2/4 (50%), 35–40 = 2/13 (15,3%) and >40 = 0/4 (0%)), and women with lower FSH levels (<10 = 1/2 (50%), 10–15 = 0/5 (0%) and >15 = 2/8 (25%)). Conclusions: Natural cycle would be the best alternative treatment to the oocyte donation in poor responders. The only disadvantage is the low pregnancy rate per cycle due to a high cancellation rate. This could be improved with more strict control in these unstimulated cycles. Supported by: IVI.