The activated protein C-resistance (APC-R) method based on APTT was used in 40 non-pregnant multiparas (control group) and 55 patients with abortion of unknown origin (experimental group) in order to explore the relationship between APC-R and recurrent abortion. A significant difference in APC-R-positive rate was found (P < 0.01) between control group and experimental group, with the rate being 5% in the controls and 25.5% in the experimental group. And the APC-R-positive rates in the patients with only twice abortions and the patients over-3-time abortions were 22.6% and 29.2%, respectively (P > 0.05). The APC-R-positive rate, which was 37.9% in the patients of late abortion, was much higher than that in the patients of early abortion. It is concluded that APC-R has something to do with recurrent abortion, and is closely related to late abortion, but bears no obvious relationship with times of abortions.