The absence of semen fructose and low ejaculate volume in men with congenital absence of the vas deferens have been attributed to an associated agenesis of the seminal vesicles. Because vasography and retrograde seminal vesiculography cannot be performed in these men, this association has never been confirmed reliably. Therefore, we performed computerized tomographic scans of the seminal vesicles on 26 men with absence of the vas deferens. We found seminal vesicles bilaterally in 12 of these men, unilateral hypoplasia or absence in 8 and bilateral hypoplasia or absence in 6. Four men with normal seminal vesicles and 1 with unilateral hypoplasia underwent exploration in an attempt to find reconstructable vasa. We failed to identify a vas deferens in any of these men. These observations suggest that negative semen fructose and low ejaculate volume in men with absence of the vas deferens may be owing to agenesis or obstruction of the ejaculatory ducts rather than absent seminal vesicles.