Congenital anomalies of the epididymis are frequent. Their understanding requires familiarity with their embryological origins. They are important given their impact on fertility. INTRODUCTION. EMBRYOLOGIC REMARKS John Hunter (1728-1793), the great Scottish surgeon whose many contributions advanced medicine in general and pathology in particular, was among the first to provide detailed descriptions of the male genital system in many species, including his elegant account of absent ductus deferens in a man: ''In dissecting a male subject, in the year 1755, for a side view of the contents of the pelvis, I found a bag on the left side, lying contiguous to the peritonaeum, just on the side of the pelvis where the internal iliac vessels divide above the angle of reflection of the peritonaeum at the union of the bladder and rectum. The left vas deferens was seen passing on to this bag; and what is very singular, that of the right, or opposite side, crossed the bladder, near its union with the rectum, to join it. I traced the left vas deferens down to the testicle; but, on following the right through the ring of the external oblique muscle, I discovered that it terminated at once, about an inch from its passage out of the abdomen, in a blunt point, which was impervious. On examining the spermatic chord from this point to the testicle, I could not find any vas deferens; but, by beginning at the testicle, and tracing the epididymis from its origin, about halfway along where it lies upon the body of the testicle, I perceived that it at first became straight, and soon after seemed to terminate in a point" [1]. Malformations of sperm excretory ducts have been recorded in the medical literature for more than two centuries. Mainly in the last two decades has interest in this field increased, thanks to new medical developments. These include a more complete assessment of infertile patients and modern techniques, such as transrectal