Background: Currently, cardiovascular disorders are the primary cause of mortality in the world and constitute a serious medical problem. Blood coagulation is an essential process to prevent excessive blood loss through injured blood vessels; however, abnormal blood clotting in the blood vessels can result in fatal cardiovascular disorders. This study investigated the in vitro anticoagulant activity of Meriandra dianthera crude extract and its fractions and their erythrocyte membrane stabilizing activity. Methods: The plant leaves were extracted by a decoction method and were further fractionated by a liquid-liquid partition with a solvent of crescent polarity. The in vitro anticoagulant activity of the plant extract and its fractions was assessed by PT and APTT assays, while the membrane stabilizing activity was determined through hypotonic induced hemolysis. Results:The crude aqueous leaf extract of Meriandra dianthera significantly (P < 0.001) prolonged the intrinsic clotting pathway measured by APTT by specifically acting on the intrinsic coagulation pathway. By using liquid-liquid fractionation, the residual aqueous fraction was identified as the fraction responsible for the anticoagulant activity of the crude extract as it significantly (P<0.001) prolonged APTT while the other fractions failed. Both the crude extract and its aqueous residue fraction did not affect the extrinsic coagulation pathway measured by PT. In the membrane stabilizing assay, crude extract and aqueous residue fraction showed the highest membrane stabilizing activity. Conclusion:The crude extract and its aqueous residue fraction showed a potent in vitro anticoagulant and membrane stabilizing activity, which shows the potential of the plant's leaves as a new source of bioactive molecules for coagulation-related disorders.