Patients with spondyloarthritis, already treated by TNF blocker (adalimumab, etanercept or infliximab), and in stable low disease activity for at least 6 months, will be randomized into 2 groups: either keeping on their usual treatment with stable doses or progressive spacing of injections of their treatment. Follow-up will be done every 3 months during 12 months, with regular monitoring of disease activity and, in patients from the group "spacing", modification of the rhythm of injections according to health state and predefined protocol.

Inclusion Criteria:

• Adult patients with spondyloarthritis according to ASAS criteria
• Stable low disease activity for at least 6 months
• Already treated by TNF blocking drug (adalimumab, etanercept or infliximab)

Exclusion Criteria:

• Raised acute phase reactants
• participation in another clinical trial
• Structural progression of peripheral joint damage
• Scheduled surgery within 12 months
• pregnancy