Effects of Etanercept on the Heart, Veins and Thickness of Certain Major Arteries In Ankylosing Spondylitis Patients

Inclusion Criteria:

1. Diagnosis of AS, as defined by Modified New York Criteria for Ankylosing Spondylitis.
2. AS with active disease as defined by Bath Ankylosing Spondylitis Disease Activity Index (BASDAI, see Attachment 4) >= 4 at screening visit.
3. Patients capable, in the opinion of the investigator, of complying with the treatment schedule and doses throughout the 52 weeks
4. Agreement by male subjects who are not surgically sterile and female subjects who are not surgically sterile or postmenopausal to use reliable methods of birth control for the duration of the study.
5. Ability to self-inject drug or have a designee who can do so.
6. Ability to store injectable test article at 2ºC to 8ºC.

Exclusion Criteria:

1. Pregnancy confirmed by test taken at screening in all women except those who were surgically sterile or at least 1 year postmenopausal. Sexually active women of childbearing potential participating in the study must use a medically acceptable form of contraception that needs to be continued for 15 days following discontinuation of the test article.