Objective To describe an unusual case of a sextuplet gestation after IVF and transfer of a single blastocyst. Design Case report. Setting University-based IVF clinic. Patient(s) A 32-year-old female with secondary infertility undergoing IVF-ET. Intervention(s) Transvaginal oocyte retrieval, transfer of a single blastocyst, and multifetal pregnancy reduction. Main Outcome Measure(s) Ultrasound determination of pregnancy viability. Result(s) Six intrauterine gestational sacs, each with a fetus having cardiac activity, reduced to a triplet gestation. Conclusion(s) Physicians should consider advising patients undergoing IVF-ET to abstain from unprotected intercourse at least 4 days before the anticipated oocyte retrieval. Incomplete aspiration of ovarian follicles is uncommon but not rare and can lead to a higher order multiple pregnancy if recent unprotected intercourse has occurred in this setting.