Background: Globally there is a dearth of access to safe second trimester abortions. Preoperative cervical ripening improves the safety of these procedures. Prior clinical and pharmacokinetic studies suggest misoprostol and Dilapan-S are effective for faster cervical ripening, allowing early second trimester abortions to be performed in a single day. However, it is unknown which agent is best. Objectives: To compare the efficacy and acceptability of same day misoprostol and Dilapan-S for cervical ripening before early second trimester surgical abortion in nulliparous and multiparous women. Methods: In this randomized, double-blinded controlled trial patients received misoprostol 400 micrograms buccally or one 4 millimeter Dilapan-S rod three to four hours before dilation and evacuation at 12 0/7 to 15 0/7 weeks gestation. The primary outcome measured was level of preoperative dilation. A sample size of 32 nulliparous and 32 multiparous subjects in each treatment arm is based on 90% power and alpha of 0.05. For the primary analysis, we will compare initial cervical dilation between the two treatment groups and stratify by parity using a two-way ANOVA. Secondary outcomes include ease of further mechanical dilation, procedure time, complication rates, and patient pain and satisfaction. Results: Of the 125 women who completed study procedures between January 26, 2009 and December 31, 2011, 61 subjects were randomized to one rod of Dilapan-S and 64 were randomized to 400 mcg buccal misoprostol. There was no statistically significant difference between the two groups with regards to subjects’ age in years (p=0.9206), gestational age in days (p=0.9113), body mass index (p=0.6117), gravidity (0.6305), parity (p=0.8745), prior terminations (p=0.6445), prior miscarriages (0.8714), time spent in recovery room post-procedure (p=0.7060), or insurance used (p=0.7290).