OBJECTIVE To develop a questionnaire measuring quality of life in ankylosing spondylitis (AS). METHODS A focus group technique contributed to the generation of an AS-specific questionnaire using the Arthritis Impact Measurement Scales 2 (AIMS2) (12 dimensions), supplemented with items from the Health Assessment Questionnaire for the Spondylar-thropathies, as well as original new items. Patients from a self-help group provided data to assess the validity (n = 146) and reproducibility (n = 43) of the AS-AIMS2. RESULTS The focus group generated a thirteenth dimension including 6 items labeled "spine mobility." Principal component analyses on AS-AIMS2 showed satisfactory dimensionality (74.1% of variance explained), high internal consistency (Cronbach's alpha = 0.78-0.91), significant convergent validity of the new dimension with spine pain and mobility, and good reproducibility in the 13 dimensions and 5 components (intraclass correlation coefficient = 0.7-0.9). The scores in each component of the AS-AIMS2 showed a marked deterioration of quality of life in these young patients. CONCLUSIONS The disease-specific AS-AIMS2 questionnaire should help improve care management in AS.