Clinical signs of chronic epididymitis in a stallion included recurrent signs of inguinal pain--retraction of the right testis into the inguinal area, resentment of palpation of the right testis, and right-sided scrotal swelling. The tail of the right epididymis was firm and seemed to be adhered to the testis. The tail of the left epididymis felt firmer than normal. Ultrasonographically, the diameter of the head of the epididymis was considered larger than normal, was hyperechoic in relation to the right testis, and had an irregular border. Several bright 1- to 5-mm-diameter echogenic areas that alternated with less echogenic areas were seen in the head of the right epididymis. Ultrasonographic findings were interpreted as fibrosis attributable to chronic inflammation. Unilateral castration (right-sided) was performed, but the prognosis was guarded because of presumed involvement of the left epididymis.