BACKGROUNDThe leaves of African plants are widely employed in Nigeria to control bleeding from wounds. This work is aimed at evaluating the haemostatic effects of Vernonia amygdalina (VA/bitter leaf) and Chromolaena odorata (CO/sunflower) leaves on some haemostatic parameters.METHODSA laboratory study of experimental design was conducted involving 35 Wistar rats that were randomized into seven groups. Groups 1 and 2 received leaf extracts of VA at concentrations of 150 and 250mg/kg BW, respectively; groups 3 and 4 received leaf extracts of CO at 150 and 250mg/kg BW; groups 5 and 6 received combined leaf extracts of VA and CO at 150 and 250mg/kg BW, respectively, for 30 days. The last group 7 as control group received only water. Parameters investigated were clotting time (CT), fibrinogen concentration, prothrombin time (PT), activated partial thromboplastin time test (APTT), factor VII, protein C and D – dimer.ResultsThere was a significant reduction in CT, fibrinogen concentration and PT in the intervention groups compared to controls (p<0.01). There was no significant difference in APTT, factor VII and protein C in the intervention groups compared to the controls (p>0.05). D-dimer levels were observed to increase significantly in rats treated with 150mg/kg BW of VA and 150mg/kgBW of the combined leaf extracts (VA/CO) compared to the controls (p<0.05).ConclusionThe VA and CO extracts reduced CT, PT, fibrinogen concentrations and increased D-dimer levels in rats. This study suggests the possible incorporation of the leave extracts of VA and CO in bleeding diathesis as well as in coagulation studies.