In our study, the rate of pregnancy by transfer and puncture was not significantly different in unexplained and in tubal infertility, but the mean number of transferred embryos was significantly higher in the first group. To explain these data, we compared the quality of embryos in 32 punctures realized among 29 women with unexplained infertility and in 171 punctures planned among 156 women with tubal infertility. The percentage of embryos with 4 or more blastomeres was significantly lower in the unexplained infertility group than in the pure tubal infertility group.