Objective: To assess the effect of laser biopsy for preimplantation genetic diagnosis (PGD) on embryo development.Design: A retrospective analysis comparing development between matched biopsied and non-biopsied embryos.Materials and methods: There were 36 patients in the biopsy group and 56 controls. Embryo development was observed from day 3 through day 5 in both groups, with the biopsy group having undergone blastomere biopsy of one to two cells on day 3, and the control group undergoing no laser or biopsy procedures. Zona pellucida (ZP) dissection was undertaken with a Class 1 1.48μm wavelength IR laser, using a double pulsed 1.0msec burst with 140mW power at the target (Zilos Laser System, Hamilton Thorne Research, Beverly, MA, USA). Transfer of genetically normal embryos was carried out on day 5, and no further development was recorded for the majority of embryos due to embryo arrest or genetically abnormal results yielding embryos unsuitable for cryopreservation. Control patients were matched with the biopsy group for both age and insemination method (Conv=conventional IVF; ICSI=intracytoplasmic sperm injection). Both groups consisted of patients undergoing IVF treatment during the laboratory series from August 2002 to April 2003. Maternal ages given for the patient groups are averages; actual ranges were 26–44 years for the biopsy group, and 26–43 years for the control group. Tabled 1Results: # Embryos refers to the average number that underwent biopsy in the biopsy group, and the number continuing development through day 5 in both groups. % Prog refers to the percentage of embryos that showed forward development from day 3 to day 5; % Arrest refers to the percentage of embryos that showed no change in development; and % Deg refers to the percentage of embryos that degenerated during this time.Conclusions: Laser-assisted biopsy with the removal of one to two blastomeres for the purpose of PGD analysis does not appear to have a detrimental effect on the continued general development of those embryos, when compared to embryos from patients of comparable ages and insemination methods not undergoing any laser or biopsy procedures. Objective: To assess the effect of laser biopsy for preimplantation genetic diagnosis (PGD) on embryo development. Design: A retrospective analysis comparing development between matched biopsied and non-biopsied embryos. Materials and methods: There were 36 patients in the biopsy group and 56 controls. Embryo development was observed from day 3 through day 5 in both groups, with the biopsy group having undergone blastomere biopsy of one to two cells on day 3, and the control group undergoing no laser or biopsy procedures. Zona pellucida (ZP) dissection was undertaken with a Class 1 1.48μm wavelength IR laser, using a double pulsed 1.0msec burst with 140mW power at the target (Zilos Laser System, Hamilton Thorne Research, Beverly, MA, USA). Transfer of genetically normal embryos was carried out on day 5, and no further development was recorded for the majority of embryos due to embryo arrest or genetically abnormal results yielding embryos unsuitable for cryopreservation. Control patients were matched with the biopsy group for both age and insemination method (Conv=conventional IVF; ICSI=intracytoplasmic sperm injection). Both groups consisted of patients undergoing IVF treatment during the laboratory series from August 2002 to April 2003. Maternal ages given for the patient groups are averages; actual ranges were 26–44 years for the biopsy group, and 26–43 years for the control group. Tabled 1 Results: # Embryos refers to the average number that underwent biopsy in the biopsy group, and the number continuing development through day 5 in both groups. % Prog refers to the percentage of embryos that showed forward development from day 3 to day 5; % Arrest refers to the percentage of embryos that showed no change in development; and % Deg refers to the percentage of embryos that degenerated during this time. Conclusions: Laser-assisted biopsy with the removal of one to two blastomeres for the purpose of PGD analysis does not appear to have a detrimental effect on the continued general development of those embryos, when compared to embryos from patients of comparable ages and insemination methods not undergoing any laser or biopsy procedures.