Résumé : Among 429 patients admitted in our in-vitro fertilization (IVF) programme during the last 3 years, 106 experienced cancellation of one or more treatment cycles. A low oestrogen (E 2) response represented by far the main reason for cancellation (144/184). Significantly lower clinical pregnancy rates were found in the group of patients with low E 2-cancelled cycles (E 2CC) as compared to the rest of the IVF population (13 versus 37%). Further comparison between these groups showed only little or no difference in the mean age of patients, basal FSH levels, number of egg collections, rate of oocytes obtained and fertilized per trial and mean embryonic vitality score. A large majority of E 2CC patients were found to belong to the tubal infertility group (75%) as opposed to a lower proportion of tubal cases among other IVF patients (56%). E 2CC tubal patients showed a lower pregnancy rate than other cases with abandoned cycles and also than other tubal patients (8.9 versus 25 and 35%, respectively). Mean numbers of previous laparotomies, of attempts at oocyte retrieval and of oocytes recovered per trial were similar in tubal patients with or without E 2CC. However, in the E 2CC tubal group mean age and basal FSH levels were somewhat higher, whereas E 2 peak values and fertilization rates were lower, leading to a greater proportion of trials without embryo transfer. Embryonic scores and the E 2/P ratio at day 3 of the luteal phase did not differ signficantly. It may be concluded that cancelling of a cycle because of a low E 2 response in a patient with tubal infertility is indicative of a poor prognosis in further IVF trials.