Objectives: To evaluate the results of embryo transfer on day 3, and day 5 and the relationship with the wife's age. Material and methods: Cross-sectional description of 320 infertile couples undergoing in vitro fertilization at the Department of Reproductive Assistant, A Thai Nguyen Hospital. Evaluation of embryo transfer results in embryo cleavage on day 3, blastocyst on day 5; compares the results to the wife's age group < 35 and ≥ 35 years old. Results: The rate of βhCG positive, fetal heart, and pregnancy progression in the day 5 embryo transfer group were statistically significantly higher than in the transfer day 3 fresh and frozen embryo groups. In the cases of the wife < 35 years old, the rate of pregnancy was highest in the group of day 5 embryo transfer, the lowest in the group of fresh embryo transfer on day 3, the difference was statistically significant.