OBJECTIVES: The Health Assessment Questionnaire (HAQ) is a popular tool used to measure disability. However, few studies have assessed its psychometric properties in patients with Spondyloarthritis (SpA). Hence, we aimed to assess the reliability and validity of the HAQ in patients in SpA in Singapore. METHODS: Cross-sectional data from a registry of 196 patients with SpA recruited from a dedicated tertiary referral clinic in Singapore from 2011-2014 was used. Survey was administered in English. Analyses were guided by the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) framework. Internal consistency reliability was assessed using Cronbach’s alpha. Convergent and divergent validity were assessed through correlation of the summary score and the 8 domain scores of the HAQ with other health outcome measures - Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Fatigue Index (BASFI), Bath Ankylosing Spondylitis Global Score (BASG), pain, Patient’s Global Assessment (PGA), and Short Form-36 Health Survey (SF-36) Physical Component Score (PCS) and Mental Component Score (MCS); Spearman’s rank correlations with p-values less than 0.0016 (adjusting for multiple testing) were deemed significant. RESULTS: Among 196 patients (155 Males: 41 Females, Median (Range) Age: 36 (17-70), 166 Chinese: 30 Non-Chinese), the HAQ showed a high internal consistency of 0.78 to 0.84. Convergent validity was supported- the 8 domains and summary scores of the HAQ were significantly correlated with BASDAI, BASFAI, pain, PGA and SF-36 PCS. Divergent validity was also established- correlation of SF-36 MCS with the 8 domains and summary scores of the HAQ were not statistically significant. CONCLUSIONS: This study supports the HAQ as a valid and reliable measure of disability for use in patients with SpA.