RESUMEN
INTRODUCTION: Sacral parasitic twins originate from one fertilized ovum and they have one placenta and the same sex. CASE REPORT: A 23-year-old woman was referred to our clinic. Examination by touch revealed a mass that was in the sacral region but the borders could not be fully examined. The solid mass, which was conjoined to the sacrum, had a soft texture. The infant's appearance was macroscopically normal. When the mass was examined by palpation, there were structures which felt like extremities. The mass was 20 x 11 x 9 cm in size. CONCLUSION: The differential diagnosis should include sacrococcygeal teratoma. In our case the differential diagnosis was done by histopathologic findings. This case, which involved a tumoral formation at the sacral region in the antenatal period, was detected during delivery. A sacral parasite is a rarely seen phenomenon and as such the diagnostic information of this case could be useful.