To compare blastocyst formation when embryos were removed from the incubator only once and twice for embryo evaluation on poor-prognosis patients Conventionally, embryos were removed from the incubator two or three times to assess fertilization, cleavage embryo quality. These non-optimal conditions may affect embryonic quality. Moreover, some retrospective and prospective trial also demonstrated a benefit of group culture in human embryos. Data for this retrospective study were taken from September 2020 to March 2021 including couples had 1-5 mature oocytes and had at least one zygote.We cultured embryos in groups of less than four embryos per 30μl microdroplet. Embryos in experimental group were examined microscopically only once in fertilization day, after that they were cultured to day 5. In the control group, embryos were assessed two times on day 1, 2 (or day 3). The total blastocyst formation rate and good quality blastocyst fomation rate were used to compared two groups (this ratio is calculated as the number of blastocysts per number of mature oocytes) Number of cycles in control group and experimental group were 99 and 111. The average age of oocytes in two group were similar (36.85 vs 36.68, respectively). The number of mature oocytes were also similar (3.59 vs 3.61). The total blastocyst formation rate in coltrol group slightly more less than experimental group (52.39% vs 54.11%, respectively, p>0.05) but good quality blastocyst fomation rate significantly lower in coltrol group (47.32% vs 53.12%; respectively, p<0.05) Reduction of the embryo-evaluation time can enhance good blastocyst formation rate on poor-prognosis patients