摘要：Objective: we aimed to determine whether second- trimester abortion using isosorbide mononitrate (IMN) in addition to gemeprost is more effective and reduces side effects compared with gemeprost alone. Study design: Eighty women who were age 13 to 23 weeks’ gestation were randomly assigned to receive per vaginam either IMN 40 mg (group 1, 40 women) or placebo (group 2, 40 women) in addition to gemeprost 1 mg up to 3 times daily 3 hours apart for 2 days. Analysis of variance, a χ 2 test, and a multivariate analysis were performed. Results: Of the 72 women analyzed, 68% (group 1) and 38% (group 2) underwent abortion within day 1 (P <. 05). However, group 1 was associated with more headache (18% of women) 3 hours after induction compared to group 2 (0% of women, P=.038). Conclusion: IMN in addition to gemeprost is effective for second- trimester abortion, but is associated with more headache compared with gemeprost alone.