The results of 98 therapeutic abortions in the first and second trimester of pregnancy using F prostaglandins are reported. The prostaglandins were eigher administered by fractionated extra-aminotic PGF2 alpha, intramuscular 15-methyl PGF2 alpha or extra-amniotic or intracervical single shot 15-methyl PGF2 alpha. The induction abortion time of 13 hours and 15minutes for the single shot and 14 hours and 28 minutes for the intramuscular administratic with the prostaglandin derivatives is shorter than with natural prostaglandins which showed a mean induction to abortion time of 19 hours and 30 minutes. The blood loss was low in all groups at approximately 75 mls. Side effects are least with the single shot method (11%). Two patients had nausea, two patients had vomiting, three patients had flush or lower abdominal cramps. The intramuscular administration showed the highest frequency of side effects (80%). In the first trimester the single shot method always leads to sufficient cervical dilatation although the abortion rate was low at 59%. During the second trimester a high abortion rate is found. Therefore this method can be recommended for therapeutic abortions.