The study is designed to compare the risk of cardiovascular events (heart attacks, strokes) in patients receiving either etoricoxib or diclofenac. It will also compare the gastrointestinal tolerability of the two medicines. The study will be conducted in patients with either rheumatoid or osteo-arthritis.

Inclusion Criteria:

• Patient has a clinical diagnosis of either Osteoarthritis or Rheumatoid Arthritis and in the opinion of the investigator will require chronic nonsteroidal anti-inflammatory or COX-2 inhibitor therapy for at least 1.5 years

Exclusion Criteria:

• Concurrent medical or arthritic disease that could confound or interfere with efficacy evaluation.
• Concomitant therapy of warfarin, heparin, high-dose aspirin (>100 mg/day).
• Impaired kidney function, clinical gastrointestinal malabsorption, congestive heart failure with symptoms that occur at rest, unstable angina, uncontrolled high blood pressure, active hepatitis/hepatic disease