A saline suspension of Lumbricus rubellus earthworm powder (EWP) was administered to rats (1 g/kg/day) orally for 15 days to evaluate an oral effectiveness for thrombotic disorders. Blood was drawn at 2-day interval after the administration. Several parameters for antithrombotic, anticoagulant and fibrinolytic activities were measured, including platelet aggregation, clotting time, plasmin activity and the levels of FDP (fibrin/fibrinogen degradation products), D-dimer, and t-PA antigen. It did not affect platelet aggregation induced by ADP and collagen but anticoagulant activity (aPTT and TT) was gradually increased to two-folds for the first 5 days of administration and back to normal. Fibrinolytic activity of euglobulin fraction was highest on the 11 th day after the administration. The level of FDP was elevated to be comparable to the positve control$ (5-10 {mu}g/ml)$ after 9-day treatment. Oral administration of the EWP could also reduce the formation of venous thrombus induced with viper venom. Complete blood count (CBC) profiles were within normal ranges except for a slight increase in white blood cells after the oral administration for 15 days. These results suggested that the EWP may be valuable for the prevention and/or treatment of thrombotic diseases.