Thirty-nine patients with abnormally elevated levels of serum beta subunit of human chorionic gonadotropin (beta-hCG) were studied to determine whether findings at magnetic resonance (MR) imaging are specific for primary molar disease, persistent gestational trophoblastic disease (GTD), incomplete abortion, and ectopic pregnancy. Among the latter three groups, the only significant differences were a higher prevalence of endometrial distention in the group with incomplete abortion (P < .0035) and the absence of junctional zone disruption in the group with ectopic pregnancy (P < .05). In the group with primary molar disease, total intrauterine volume was significantly increased (P < .001), and endometrial distention and presence of an endometrial mass had a significantly higher prevalence than that in the persistent GTD groups with (P < .04) or without (P < .001) metastases. Myometrial or extrauterine disease was identified in 65% of the patients with persistent disease and a beta-hCG level greater than 500 mIU/mL (500 IU/L). Thus, although MR imaging findings in persistent GTD, incomplete abortion, and ectopic pregnancy are relatively nonspecific, MR imaging can depict invasive disease that may alter therapeutic management in patients with documented GTD.