The Mayer-Rokitansky-Kuster-Hauser syndrome is composed of vaginal atresia with other variable Mullerian duct abnormalities such as bicornuate or septated uterus. The fallopian tubes, ovaries, and broad and round ligaments are normal. Unilateral renal and skeletal anomalies are associated in 50% and 12% of cases respectively. Patients have a normal female karyotype and normal secondary sexual development. Previously, one had to rely on radiographic contrast studies and surgical exploration for accurate definition of the reproductive tract anatomy. The authors performed ultrasound (US) examinations on 12 patients, aged 5 days to 18 years, with the Mayer-Rokitansky syndrome. US allowed correct identification of the genitourinary anomalies found in these girls, including eight cases of unilateral renal agenesis; one absent, one rudimentary, and ten duplicated or obstructed uteri; eight duplicated or obstructed vaginas; and associated complications such as an endometriosis. Eight of the patients had lower abdominal pain, often cyclical in nature. The findings demonstrate that high-resolution, real time US in conjunction with water vaginography permits the anatomy of these complex anomalies to be defined.