80 patients with ankylosing spondylitis were randomized to receive a Chinese patent medicine, 0.6g Kunxian, or a placebo drug, 3 times daily for 12 weeks. The purpose of this study was to determine the efficacy of Kunxian, measured using the Assessment of SpondyloArthritis international Society (ASAS) 20 response rate. Other outcomes included ASAS 40, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) 50, Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), and Ankylosing Spondylitis Disease Activity Score on the basis of C-reactive protein level (ASDAS-CRP). Findings indicated a significantly greater proportion of ASAS 20 response rates at week 12 in the Kunxian group compared to the placebo group. BASDAI 50 and ASDAS-CRP were comparable between groups at week 12.