To evaluate the predictive value for implantation and pregnancy rates of the number of embryos that reach the eightcell stage with less than 20%fragmentation (good quality embryos) on day 3. Prospective observational study. Private IVF center. One hundred eightynine women undergoing IVF,or intracytoplasmic sperm injection with at least four zygotes, who have had three embryos transferred on day 3. None. Pregnancy rate and implantation rate. All patients (n = 189) had 3 embryos transferred. The patients were divided in five groups according to the number of good quality embryos on day 3 (0, 1, 2, 3, >3; respectively). For the five groups, the pregnancy rates were 2.9%, 33.3%, 45.5%, 39.4%, and 64.3%; the implantation rates were 2.0%, 17.0%, 20.5%, 19.3%, and 35.7%. No statistically significant differences in pregnancy rate or implantation rate were found for groups 1, 2, and 3 (when 1, 2, or 3 good quality embryos were present). The data were also analyzed after pooling these three groups. A statistically significant difference in pregnancy rate and implantation rate was found for group 0 (no good quality embryos), groups 1, 2, and 3 (1, 2, or 3 good quality embryos), and group >3(>3 good quality embryos). The number of good quality embryos available on day 3 is a strong predictive value for both pregnancy rate and implantation rate. When good quality embryos are present on day 3, only two embryos should be transferred to minimize multiple pregnancies. To evaluate the predictive value for implantation and pregnancy rates of the number of embryos that reach the eight-cell stage with less than 20% fragmentation (good quality embryos) on day 3. Prospective observational study. Private IVF center. One hundred eighty -nine women undergoing IVF, or intracytoplasmic sperm injection with at least four zygotes, who have had three embryos transferred on day 3. None. Pregnancy rate and implantation rate. All patients (n = 189) had 3 embryos transferred. The patients were divided in five For the five groups, the pregnancy rates were 2.9%, 33.3%, 45.5%, 39.4%, and 64.3 (0, 1, 2, 3, %; the implantation rates were 2.0%, 17.0%, 20.5%, 19.3%, and 35.7%. No statistically significant differences in pregnancy rate or implantation rate were found for groups 1, 2, and 3 (when 1, 2, or 3 good quality embryos were present). The data were also analyzed after pooling these thre e groups. A statistically significant difference in pregnancy rate and implantation rate was found for group 0 (no good quality embryos), groups 1, 2, and 3 (1, 2, or 3 good quality embryos), and group> 3 (> 3 good quality embryos). The number of good quality embryos available on day 3 is a strong predictive value for both pregnancy rate and implantation rate. When good quality embryos are present on day 3, only two embryos should be delivered to minimize multiple pregnancies.