We report the unusual case of a 78-year-old man who presented with obstructive bowel symptoms and a 2.5-cm presacral mass. The mass was excised and found on pathologic examination to be ectopic prostate tissue complete with a muscular stroma. Review of the literature revealed a number of case reports describing variably sized fragments of ectopic prostate tissue involving a variety of organs, including spleen, uterine cervix, bowel wall, pericolic fat, anal submucosa, seminal vesicle, testis, and urinary bladder. However, to our knowledge, this case is unique in that it presented as a relatively large, isolated presacral mass causing functional bowel impairment. The ectopic location can be related to the normal embryonic development of the prostate, rectum, and bladder.