▴ Etanercept is a dimeric fusion protein based on the p75 tumor necrosis factor (TNF) receptor. It binds to TNFα and blocks its biological activity.▴ Subcutaneous etanercept is effective in the treatment of rheumatoid arthritis, psoriatic arthritis, and polyarticular-course juvenile rheumatoid arthritis. More recently, etanercept has shown efficacy in the treatment of adults with ankylosing spondylitis.▴ In randomized, double-blind, placebo-controlled trials, subcutaneous etanercept 25mg twice weekly for 6–24 weeks significantly reduced disease activity in patients with active ankylosing spondylitis. In the largest trial, etanercept produced a response rate of 57% compared with 22% for placebo after 24 weeks (response was determined via the validated ASAS 20 response criteria developed by the Assessments in Ankylosing Spondylitis [ASAS] Working Group).▴ Etanercept therapy significantly improved health-related quality of life in patients with ankylosing spondylitis compared with placebo. The greatest improvements in a 16-week study were seen in the domains of physical functioning, physical role, bodily pain, vitality, and social functioning.▴ Etanercept was generally well tolerated, with few serious adverse events or treatment withdrawals. The most common adverse events were injection-site reactions and minor upper respiratory tract infections.Table. Features and properties of etanercept (Enbrel®) in active ankylosing spondylitis