Abstract: Objective To assess the value of bath ankylosing spondylitis disease activity index（BASDAI） and mini-BASDAI for diagnosis of ankylosing spondylitis（AS）. Methods Patients with AS were divided into "P+" group and "P-" group according to the involvement of their peripheral joints.BASDAI was used to assess the disease activity of patients with ankylosing spondylitis and mini-BASDAI was calculated by omitting questions 3 and 4 in BASDAI. Results A total of 264 AS patients were included in this study.The BASDAI,mini-BASDAI,BASFI,BASMI,ESR,and CRP were significantly higher in "P+" group than in "P-" group.The value of mini-BASDAI was higher than that of BASDAI in both groups.However,no significant difference was found in other markers of disease activity between the two groups. Conclusion Mini-BASDAI is not advantageous to BASDAI in assessing disease activity of patients without involvement of peripheral joints and BASDAI remains a valid indication.