This chapter focuses on biopsy procedures at subsequent stages of embryo development after fertilization with particular emphasis on blastocyst biopsy. Since the advent of preimplantation genetic diagnosis (PGD) there have been three methods primarily used to breach the zona pellucida to facilitate the removal of cells for testing. The first approach utilizes a mechanical technique called partial zona dissection (PZD). The second method developed to breach the zona pellucida involves chemical digestion with acidified Tyrode's solution. Zona drilling with acid has never been the method of choice prior to polar body biopsy. The third method for creating an opening in the zona pellucida involves the use of a computer-controlled non-contact 1480 nm infrared diode laser beam. All three methods for breaching the zona pellucida have been utilized to facilitate cleavage-stage biopsy. An excellent blastocyst culture system is required for successful trophectoderm biopsy.