The prognostic value of the score of embryo transfer (SET) was assessed on 1079 embryo transfers in a homogene population of patients. The SET is obtained adding the embryo score (ES) of each transferred embryos. ES is based both on the conventional parameters of embryo morphology, and on the 4-cell stage which is the optimum division stage regarding implantation. The SET is strongly correlated with the pregnancy rate (p < 10-5), and is, with the mean score of transferred embryos (MSTE), the most sensitive and specific parameter of all studied parameters. However, embryo quality seems not to be correlated with miscarriages.