In an attempt to define better the sonographic findings of adenomyosis of the uterus, we reviewed sonograms in seven cases of pathologically proven extensive adenomyosis without associated uterine diseases. In all cases, the uterus was enlarged. In five cases, the posterior wall of the uterus was thickened, and echoes in the endometrial cavity were eccentric. Six cases showed a slight decrease in uterine echogenicity. One case had sonographic findings suggestive of a calcified leiomyoma. The diagnosis of adenomyosis cannot be made conclusively by sonography. However, it can be suggested if the uterus is slightly enlarged and if the posterior portion of the myometrium is anechoic and thickened.