A new approach to terminate very early pregnancy was tried on 49 healthy women who were proven to be pregnant from 31 to 47 days from their last menstrual period. All pregnancies were confirmed either by UCG or serum HCG-B subunit. (15S)-15-Methyl PGF 2a Methyl Ester in a suppository form was administered in two separate doses: 1.0 mg initial dose followed by 3.0 mg one hour later. Patients were kept under observation for 8 hours. Blood sampling for progesterone, HCG-B, and prostaglandin levels were assayed at 0 °, 30′, 1 °, 4 °, 8 ° and 14 days. Patients were re-examined at a two week follow-up visit. Pelvic examination and pregnancy tests were performed to confirm whether the pregnancy was successfully terminated. There were no significant changes in serums progesterone and HCG-B levels during the 8-hour observation period. Both levels declined significantly to very low levels at 14 days post-therapy, confirming the clinical impression of successful termination of pregnancy. Plasma prostaglandin levels rose as early as 30 minutes after initiation of therapy, peaked at 4 hours and declined gradually afterwards. Most side effects such as nausea, vomiting, diarrhea and cramps, although clinically manageable, were still bothersome. One patient experienced an episode of vasovagal syncope. The majority of patients required medical observation up to 6 hours. Clinical implications of this new approach of termination of very early pregnancy are discussed.