The object of this study was to compare intravaginal misoprostol and dinoprostone (prostaglandin E2) for second-trimester pregnancy termination, and to examine the role of the nitric oxide donor, glyceryl trinitrate, as a possible alternative to prostaglandins to induce cervical ripening in second-trimester pregnancy termination. This was a randomised clinical trial. The trial involved pregnant women between 13 and 28 weeks' gestation admitted with clear medical or obstetric indications for pregnancy termination, and was carried out in the department of obstetrics and gynecology, Assiut University Hospital, Egypt. Patients were classified into Group A, where pregnancy termination was induced by vaginal misoprostol 100 micrograms every 4 hours with a maximum dose of 500 micrograms; Group B, where induction was by vaginal dinoprostone 6 mg every 6 hours with a maximum dose of 24 mg; and Group C, where induction involved vaginal glyceryl trinitrate 500 micrograms every 6 hours with a maximum dose of 2.5 mg. Twenty-four hours after the start of induction, the rate of complete abortion in the three groups was 100%, 66.67% and 0%, respectively. The rate of complete abortion was 100% in the nitric oxide (glyceryl trinitrate)-induced group after introducing a complementary procedure. The induction-abortion interval was significantly shorter, the number of doses needed was less and the maximum Bishop score reached was greater with misoprostol than with dinoprostone. A higher rate of side effects occurred with the misoprostol-induced group (74%) compared with the other two groups (46.6% and 0%). Misoprostol is a cheap, effective drug for second-trimester pregnancy termination with short induction abortion intervals but a higher rate of side effects. Prostin E2 is also effective in termination of second-trimester pregnancy but is expensive and may require high doses to be administered. Glyceryl trinitrate is an effective drug for cervical ripening (softening) but it has no role in the stimulation of uterine contractions.