Inclusion Criteria:

• Male or female (women of child bearing potential must have a negative pregnancy test prior to entry into the study)
• Aged over 18 years
• Diagnosis of stable coronary artery disease (CAD) or unstable angina (troponin negative, i.e. within the normal range for the study site) with low to moderate anatomic risk and a requirement for elective percutaneous coronary angioplasty or stent insertion with an approved device in one or more de novo-treated or re-stenotic lesions in native vessels
• Signed written informed consent

Exclusion Criteria:

• Any condition which, in the investigator's opinion, contraindicates the use of argatroban, heparin or clopidogrel or endangers the patient if he/she participated in this study.
• Known cirrhosis, hepatitis, clinically significant hepatic disorder, or history of hepatic disorder. Hepatic disorder is defined as having levels of liver function tests (bilirubin, AST (SGOT), ALT (SGPT) greater than 3.0 times above the upper limit of the normal range of local laboratory.
• Patients not currently taking aspirin
• Renal insufficiency, defined as serum creatinine greater than 2.0 mg/dL (greater than 177mmol/L)
• Platelets less than 125,000/ml
• If already taking any form of heparin prior to study enrolment, aPTT equal or greater than 35 sec or ACT greater than 160 sec
• Use of low molecular heparin (LMWH) during 12 h prior to PCI
• If taking oral anticoagulant medication prior to study enrolment, INR greater than 1.2
• Q wave MI with cardiogenic shock or thrombolytic therapy within 72 h of study dosing
• Use of GPIIb/IIIa inhibitors within prior 3 weeks
• Documented coagulation disorder or bleeding diathesis
• Lumbar puncture within the past 2 weeks
• History of previous cerebral aneurysm, haemorrhagic stroke, or thrombotic stroke within the past 6 months
• Active, uncontrolled peptic ulcer disease or any gastrointestinal bleeding or genitourinary bleeding within 3 months prior to study enrolment
• Major surgery, serious trauma, puncture of non-compressible vessel, or biopsy of parenchymal organ within prior 2 months
• Planned staged procedure, planned rotational atherectomy, directional coronary atherectomy, brachytherapy, or thrombectomy catheters
• Planned surgical intervention other than study procedure within next 7 days
• Presence of greater than 50% stenosis of unprotected left main coronary artery
• Severe peripheral vascular disease, precluding femoral access
• History of vasculitis
• Uncontrolled hypertension defined as greater than 180/120 mmHg
• Pregnancy (exclusion by routine urine test)
• Lactating woman
• Woman of children bearing age who are or were not using accepted contraceptive methods
• Participation in other clinical trials of investigational products within 3 months prior to study enrolment
• Terminally ill patients with a life expectancy of < 3 months