Vasoseminal vesiculographies before and after ejaculation were compared in 16 cases of male sterility. In 12 cases the contrast medium was excreted into the ejaculate and the contours of the seminal vesicles were contracted after ejaculation. In 4 cases, however, there was little or no contraction of the seminal vesicles. Here the seminal tracts were considered to be abnormal and this dysfunction seems to be the cause or at least one of the cofactors responsible for sterility. The degree of excretion of contrast medium into the ejaculate seems to depend on the function of the seminal tract. Therefore, a postejaculation seminal vesiculogram is useful as a parameter for estimating the function of the seminal tract.