Primary non-obstructive megaureter is rarely first diagnosed in adult life. The clinical and radiographic findings in 11 adults presenting with this condition are reviewed. The commonest complaint was pain. In all cases the diagnosis was suggested by intravenous urography, which was usually the initial diagnostic test. Confirmation was aided chiefly by micturating cystography and retrograde pyelography. Cystoscopy was normal. The radiologist can make an early diagnosis in this condition, which requires no treatment, in the absence of complications.