The delivery of conjoined twins is a rare occurrence, and few physicians will be called upon to handle the problems of birth and survival of these infants in a lifetime of practice. However, with the general improvements in medicine and surgery, one may anticipate more of these twins to survive and present the clinician with many difficulties. Aird has made an estimate, based on his own experience and an excellent review of the subject,1 that there will be a half-dozen cases of conjoined twins capable of being separated annually. We therefore feel that, despite the rarity of the condition, the experience in this matter should be documented for future reference. We shall attempt to present the difficulties encountered in the case of thoracopagus twins treated at the Mary Hitchcock Memorial Hospital, with a brief discussion of the topic. The incidence of double monsters is approximately 1 per 50,000 births.