The purpose of this study was to evaluate extended safety and efficacy of etanercept in adults with Ankylosing Spondylitis.

This multicenter, open-label extension study will evaluate the safety and clinical benefit of etanercept in the treatment of Ankylosing Spondylitis in subjects previously enrolled in Protocol 16.0037.

Inclusion Criteria: - Subjects completing 24 weeks of study drug in protocol 16.0037 qualify to enroll into this study Other patients to meet the following criteria:

• Negative pregnancy test
• Subjects agree to use appropriate contraception throughout study
• Should be able to self-inject study drug or have someone who can do so
• Capable of understanding protocol and willing to provide written informed consent

Exclusion Criteria:

• Any change in NSAID or prednisone dose within 2 weeks of baseline
• Any change in hydroxychloroquine, sulfasalazine, or MTX dose within 4 weeks of baseline
• Use of DMARDs other than those mentioned above, within 4 weeks of enrollment
• Previous receipt of ani-TNF agents, other than etanercept
• Receipt of any other investigational drug within 30 days of baseline
• Grade 3 or 4 adverse event attributed to etanercept which recurred when etanercept was resumed
• Abnormality in chemistry or hematology profiles or significant concurrent medical events.