133 samples of induced early abortions using mifepristone (RU486) in combination with misoprostol (Miso) were examined. There were no significant difference in the outcome and pathological changes between the two groups with varied RU486-Miso dosages. Another 133 samples of abortus (gestational age < or = 49 days) from vacuum aspiration were used as control. The villi of RU486-Miso group showed more extensive and severer degeneration than the villi of the control group under light and electron microscopy. However, whether RU486 affects the trophoblasts directly or in directly is yet in dispute. Further investigation is needed.