The efficacy of extraovular prostaglandin E2 and intra-amniotic prostaglandin F2 alpha for pregnancy termination in midtrimester was compared. A retrospective review of pregnancy termination in midtrimester using intra-amniotic instillation of 40 mg of prostaglandin F2 alpha (n = 133) or extraovular instillation of prostaglandin E2 at a rate of 500 micrograms/hour (n = 81) was performed. Both groups had a similar mean induction-to-abortion interval (19.5 +/- 19.9 and 20.9 +/- 18.2 hours for extraovular PGE2 and intra-amniotic PGF2 alpha, respectively) and a similar success rate of abortion within the first 24 hours of initial treatment (84.0% for extraovular PGE2 and 76.7% for intra-amniotic PGF2 alpha). The two groups had a similar and low (9.8%) incidence of complications. It is concluded that either of the methods used in the study (i.e. extraovular PGE2 or intra-amniotic PGF2 alpha) can be used safely and effectively for pregnancy termination in midtrimester.