The search for improving the implantation rate of embryo transfer resulted in defining embryo quality standards, making it possible to select embryos with the best potential of implantation. A favorable uterine environment is the other primordial factor of successful embryo implantation. In addition to the endometrial thickness, which is a traditional criterion, many sonographic parameters likely to reflect the uterine receptivity state were studied. Lots of studies dealt with their predictive value and practical interest.