The purpose of this report is to compare the echogenicity of the tubal ring of an ectopic pregnancy and the corpus luteum with that of the ovary for improved detection of early ectopic pregnancy. In patients with ectopic pregnancy diagnosed at sonography on the basis of the presence of an adnexal tubal ring, echogenicity of the ring was compared with the echogenicity of the ovarian parenchyma. Twenty-six patients with tubal rings containing either a yolk sac or cardiac activity were included. Twenty-three (88%) of the 26 tubal rings had echogenicity equal to or greater than that of ovarian parenchyma. In 13 patients with ectopic pregnancy diagnosed on the basis of an empty tubal ring, 10 rings (77%) were more echogenic than the ovary. In 45 control patients with intrauterine pregnancy, the corpus luteum was more echogenic than the ovary in only 3 (7%). The tubal ring of an ectopic pregnancy is usually more echogenic than ovarian parenchyma, and the corpus luteum is usually equal to or less echogenic than the ovary. Echogenicity of an adnexal mass may help distinguish the tubal ring of an ectopic pregnancy from a corpus luteum.