Five unruptured isthmic tubal pregnancies diagnosed at laparoscopy were treated with either methotrexate/citrovorum factor rescue (MTX/CF) (n = 4) or observation alone (n = 1). Entry criteria required that the ectopic be fully visualized, no greater than 3 cm in diameter, with intact serosa, and without active bleeding. Treatment selection was based upon preoperative levels of beta-hCG with MTX/CF given to subjects exhibiting a plateaued or rising pattern and observation alone given those with falling levels. Subjects were followed with serial measurements of beta-hCG, complete blood counts, and liver function tests. In all subjects the ectopic pregnancy resolved without further surgery. Time to resolution (first day of treatment to undetectable beta-hCG) ranged from 12 to 55 days. Of the five subjects studied, follow-up hysterosalpingograms in four demonstrated tubal patency on the side of the ectopic gestation.