The purpose of this study is to assess the antibody formation to Enbrel liquid in subjects with Rheumatoid Arthritis

The purpose of this study is to assess the rate of anti-etanercept antibody formation in a larger sample of subjects on liquid etanercept than the previous study, 20020378, in a minimum of 400 subjects receiving etanercept liquid for the first time, with and without concomitant MTX therapy. The rate of neutralizing antibodies to liquid etanercept will also be assessed.

Inclusion Criteria:

• 18 years of age or older
• Must be able to self-inject or have someone who can do so for them
• Should have Rheumatoid Arthritis per ARA criteria and screening lab results per predefined value

Exclusion Criteria:

• Any prior biologic therapy for inflammatory disease
• Any prior cyclophosphamide therapy
• Not using adequate contraception
• Pregnant or breast-feeding or any significant concurrent medical condition