['To determine the effect of transvaginal ultrasound-guided ET in IVF cycles performed on patients who had previously failed to conceive from IVF and compare the results to previous cycles where ultrasound guidance was not used.', 'Retrospective clinical study.', 'Private practice IVF program.', 'One hundred twenty-nine women undergoing consecutive cycles of IVF where fresh embryos were transferred.', 'Transvaginal ultrasound guidance was used during transfer of embryos.', 'Patient age, number of ampules of gonadotropin used, maximum E(2) level, number of oocytes retrieved, number of two pronuclei embryos obtained, number of embryos transferred, mean embryo score, implantation and pregnancy rate.', 'There was no difference in any of the clinical parameters measured in IVF cycles resulting in pregnancy when transvaginal ultrasound-guided ET was used compared to the failed cycles when there was no ultrasound guidance. Of the patients who previously had failed IVF cycles and subsequently had IVF cycles with ultrasound guidance, those who became pregnant had higher mean embryo scores than those who did not become pregnant. Overall implantation and pregnancy rates were higher during the study period when transvaginal ultrasound guidance was used than in the previous 3 years when it was not used.'] Does transvaginal ultrasound-guided embryo transfer improve outcome in patients with previous failed in vitro fertilization cycles?