A group of 20 surgical specimens in 18 patients with a previously unappreciated syndrome of unremitting epididymal pain and induration 5 to 7 years after vasectomy was collected during a 2-year interval. These symptoms uniformly were unresponsive to conservative measures, including empiric antibiotics. Total unilateral or bilateral epididymectomy and partial vasectomy led to complete relief of symptoms, usually within 24 hours. Pathological examination of the specimens revealed features consistent with sequelae of long-standing obstruction. Recognition of this late post-vasectomy syndrome, which represents a major complication of vasectomy, might be expected to increase as cohorts of vasectomized individuals age.