Inclusion Criteria:

- Adult patients (> 18 years old)

- With a diagnosis of AS

- With at least one of the following evidences for active inflammation, present within
3 months before inclusion: a serum C-reactive protein (CRP) level above twice the
upper limit value of the normal range, a positive magnetic resonance imaging of the
spine or sacro-iliac joints, a vascularized enthesitis by power-Doppler ultrasound
technic.

- Presence of clinically active axial disease, as defined by 1) a Bath AS Disease
Activity Index (BASDAI) (18) of ≥ 3/10, and 2) a score of ≥ 3/10 for axial pain
(second item of BASDAI).

- Disease-modifying antirheumatic drugs (DMARDs), such as sulphasalazine, methotrexate,
hydroxychloroquine, intra-muscular gold, thiol compound, cyclosporin, intravenous
biphosphonate had to be discontinued for at least 4 weeks before inclusion.

- Dosages of NSAIDs and corticosteroid were required to remain stable for at least 4
weeks before inclusion.

- A negative pregnancy test result was required for non menopausal female patients, and
contraception during the study period and for six months after the last infusion of
infliximab was recommended to all patients of childbearing potential.

Exclusion Criteria:

- Pregnancy.

- Breastfeeding.

- Vaccination with a live organism during the last month.

- Present infection or any episode of serious infection within the last three months.

- Active malignancy within the previous five years.

- Alcohol or drug addiction.

- Severe chronic concomitant disease.

- Administration of an investigational drug within the last three months, or of any
known TNF inhibitor therapy in the past (such as thalidomide, infliximab or
etanercept).