Purpose: Preimplantation genetic screening wants to improve artificial reproductive technologies, primarily by raising the rates of pregnancy, implantation and birth. We investigated if embryos derived from oocytes detected euploid for five chromosomes implant better than those which were biopsied but where the genetic detection failed. They were nevertheless transferred, thus serving as a sham control. Method: From 2004 to 2008 we performed 104 cycles of PGS with laser biopsy of the first polar body and FISH with five chromosomes. It was offered to all patients with eight or more oocytes, free of charge. The average female age was 36 years. If no euploid oocytes were available, not detected oocytes were transferred. Result: In 104 cycles 99 embryo transfers (95 %) were performed, resulting in 28 pregnancies (27 %), 20 births (71 %) and 8 miscarriages (29 %). The implantation rate in the euploid group was 19 vs. 13 % in the not detected group (n.s.). This trend was the same independent of age and embryo morphology. Conclusion: The pregnancy rate does not differ significantly from the national average. The trend in better implantation rates of euploid oocytes justifies a continuation of studies in this matter. [ABSTRACT FROM AUTHOR]