Inclusion Criteria:

1. Males of non-pregnant females >=20 and <=80 years of age

2. Those with the diagnosis of HIT or HITTS made by the following diagnostic criteria,
or those who have positive results of HIT antibody

- diagnostic criteria of HIT

- a fall in platelet count to less than 100,000/μL or a 50% decrease in platelets
after the initiation of heparin therapy with no apparent explanation other than
HIT

- diagnostic criteria of HITTS

- those who met the diagnosis criteria of HIT

- presence of an arterial or venous thrombosis documented by appropriate
imaging technique (ultrasound, angiography etc.) or supported by clinical
evidence such as a myocardial infarction, stroke, pulmonary embolism, or
other clinical indications of vascular occlusion(absence of pulse, cold,
cyanotic extremities, etc.)

- patients with history of HIT/HITTS with positive test results (HIT antibody or
platelet function test) could be enrolled without present thrombocytopenia

3. patients willing and able to give informed consent

Exclusion Criteria:

1. any condition which in the investigator's opinion, contraindicated the use of
argatroban or endangered the patient if he or she participated in this trial

2. clinically significant or uncontrolled endocrine, renal, pulmonary, gastrointestinal,
or psychiatric disorder of sufficient severity that the investigator deemed
antithrombotic therapy with argatroban to be contraindicated

3. unexplained aPTT>200% of control at baseline

4. documented coagulation disorder or unexplained bleeding diathesis unrelated to HIT

5. lumbar puncture within the past 7 days

6. known clinical site of bleeding. Patients with a known site of clinical bleeding
could be enrolled if the investigator deemed the risk of continued thrombosis
outweighed the potential bleeding risk

7. serious liver disfunction

8. females of known or suspected pregnancy

9. breast feeding females

10. participation in other clinical drug trials within the past 30 days

11. history of hypersensitivity to argatroban

12. concomitant use of cimetidine

13. previous participation in this trial