This study assessed the influence of maternal age on the outcome of aneuploidy screening (AS) cycles for recurrent implantation failure (RIF). One hundred and sixteen couples with a history of RIF underwent 130 cycles of AS. Group A included 78 patients aged < or = 40 years (range 25-40 years) who underwent 86 cycles, while group B included 38 couples aged > or = 41 (range 41-47) who underwent 44 cycles. Fluorescence in-situ hybridization (FISH) analysis of the first and second polar bodies using probes specific for chromosomes 13, 16, 18, 21 and 22 was conducted. Euploid oocytes that cleaved were subsequently tested using the same probes on a single blastomere obtained from day 3 embryos. Chromosomally normal embryos were replaced on day 5 of culture. There was no significant difference between the two groups in the mean numbers of oocytes fertilized normally and oocytes (7.5 +/- 3.2 versus 7.2 +/- 3.6) and embryos tested (4.1 +/- 3 versus 3.4 +/-3). However, the younger age group had a significantly higher proportion of euploid oocytes/embryos, cycles reaching embryo transfer, pregnancy (43 versus 25%), clinical pregnancy (36.1 versus 16.6%) and ongoing delivery (32 versus 12.5%) rates per transfer. Preimplantation genetic diagnosis with AS for recurrent IVF implantation failure using FISH probes is therefore associated with improved outcome in women under 41 years, but has a high cancellation rate and low cycle outcome in older women.