Congenital abnormalities of the uterus are not rare and they may cause serious complications during pregnancy and labor. The ultrasonic findings are demonstrated in 4 patients. The two horns of uterus bicornis and coexisting decidual changes in the nonpregnant horn (= pseudogestational sac) can be visualised. Because of the close association between abnormalities of the genital tract in women and urinary tract malformations, the importance of analyzing the urinary tract during ultrasound examination, is emphasized.