The present study was undertaken to investigate the possible association between activated protein C resistance and first-trimester repeated abortion. Fifty-five consecutive patients with unexplained first-trimester repeated abortion and 50 healthy control women having at least one child but no previous abortion were included. Activated protein C resistance was measured in all subjects and factor V Leiden genotype testing was performed in those individuals with phenotypic activated protein C resistance. One patient with first-trimester repeated abortion and one control subject had phenotypic activated protein C resistance. Genotype analysis confirmed that both subjects were heterozygous for factor V Leiden. Our results indicate that first-trimester repeated abortion is not associated with activated protein C resistance. Factor V Leiden screening in first-trimester repeated abortion is not warranted.