This study was designed to obtain pilot clinical evidence of the efficacy, safety and acceptability of r-hLIF administered during the luteal phase after IVF/intra-cytoplasmic sperm injection (ICSI) and ET for improving embryo implantation in infertile women with a history of at least three implantation failures following ART. Based on LIF expression patterns and experimental data from animal research a role of LIF in embryo implantation is anticipated.