Linga Mathirai (LM) is a Siddha Sastric formulation indicated for treating cardiovascular diseases. The present study aimed to evaluate the efficacy of LM against the formation of thrombus and platelet aggregation on compared with Low molecular weight Heparin. In vitro clot lysis and platelet aggregation assays were employed for the study on blood samples of rat. Whole blood samples and platelets obtained by centrifugation were used for clot lysis and aggregation assay respectively. Platelet aggregation was induced by agonists Thrombin and Adenosine diphosphate (ADP). The different concentrations of LM (100, 200, 500, 1000 µL) were prepared with the adjuvant Ginger decoction for test samples and 100 µL low molecular weight heparin (LMWH) was used for treating standard group. Against clot formation and platelet aggregation, LM did not exhibit significant efficacy on compared with normal saline (control) and heparin. However, LM at its higher concentration 1000 µL exhibited significant inhibitory activity on platelet aggregation induced by both Thrombin and ADP when compared with distilled water (control). Under this study, it is concluded that the test drug Linga Mathirai had comparable and slightly lesser efficacy than low molecular weight heparin.