In vivo hatching of the blastocyst is a critical component of the physiologic events culminating in implantation. Conversely, the failure to hatch may be one of the many factors limiting human reproductive efficiency. The clinical application of assisted hatching has been proposed as one approach toward the enhancement of implantation and pregnancy rates following in vitro fertilization.  The assisted hatching procedure entails the creation of a gap in the outer area of the embryo called the zona. In the past, this was done either by drilling with an acid medium or by using a piezomicromanipulator, but currently we and most other centers are using laser vaporization of a portion of the egg shell.  Success rates following the use of assisted hatching in different ART programs have varied considerably. Well-designed studies suggest that assisted hatching might best be used in patients > 38 years old or with multiple prior failed IVF cycles.  Please note that assisted hatching with laser is the safest way to promote hatching, and this is needed if the lab is planning on doing embryo biopsy at Day 5-7.