Microfertilization technics as SUZI (sub-zonal insemination) can be indicated in cases of repeated in vitro fertilization (IVF) failure. Feminine parameters seem to play however an important role in optimalization of results. We studied 27 couples (32 IVF-SUZI cycles) who had previously presented 2 to 4 in vitro fertilization failures. These 32 cycles were divided in 2 groups according to women's age: group A < or = 35 and group B > 35 years. Results: basal FSH levels were higher in group B (6.6 +/- 3.1 mIU/ml) in comparison to group A (3.7 +/- 1.5 mIU/ml). The amount of hMG necessary to accomplish ovarian stimulation was also higher in group B (39 +/- 21 ampules) than in group A (26 +/- 11 ampules). Maximal plasma estradiol levels were higher in group A (2,775 +/- 872 pg/ml) than in group B (1,824 +/- 559 pg/ml) such as the mean number of oocytes collected and micro-injected: 11.6 +/- 4.5 versus 4.7 +/- 2.2 in groups A and B, respectively. Eight pregnancies (44%), of which 7 were ongoing pregnancies, were obtained in group A. No pregnancy was obtained in group B. Conclusions: SUZI seems to be an available technic for treatment of repeated IVF failures; our results seem to indicate a decrease in SUZI results with age of the women (> 35 years old); they suggest the opportunity of a complete investigation of feminine parameters prior to each SUZI-IVF cycle.