The purpose of this study is to evaluate the safety and efficacy of etoricoxib in the treatment of osteoarthritis of the knee.

Inclusion Criteria:

• At least 40 years of age with a clinical diagnosis of Osteoarthritis (OA)of the knee for 6 months prior to study entry (ARA class I, II, or III).
• Positive therapeutic effect from prior NSAID therapy.
• Worsening of symptoms upon withdrawal of prior treatment.
• With the exception of OA, in otherwise good health

Exclusion Criteria:

• Weight no more than 280 pounds (male or female).
• Recent, sustained use of gastroprotective agents.
• History of arthroscopy of the affected knee within 6 months prior to study entry.
• History of acute ligamentous or meniscal injury of the study joint within the previous 2 years.