A case of heterotopic triplet pregnancy after frozen-thawed embryo transfer is presented. The patient conceived after transfer of three frozen-thawed embryos at a fertility clinic where she had previously undergone laparoscopic left salpingectomy due to pyosalpinx. Approximately 4 weeks after the embryo transfer, she presented with a complaint of abnormal genital bleeding and was diagnosed by ultrasound as having a dichorionic twin pregnancy. One week later, she was referred to our hospital because of lower abdominal pain. Hematoperitoneum was suspected based on findings of low blood pressure and tachycardia. Diagnostic emergent laparoscopy demonstrated an ectopic pregnancy in the remnant isthmic portion of the left tube. Laparoscopic excision of the remnant fallopian tube was performed, but the procedure resulted in early-pregnancy loss of one of the twins. The risk of heterotopic pregnancy is not small under assisted reproductive technology. Attention should be paid to the risk of tubal pregnancy after transferring more than two embryos or controlled ovarian hyperstimulation, even after salpingectomy has been performed.