OBJECTIVE: To determine important health-related quality of life (HRQoL) domains and items within each domain affected by knee OA, and identify ethnic variations in the importance of these domains and items among three ethnic groups in a multiethnic urban Asian population in Singapore.METHODS: Focus groups were conducted among subjects with knee OA categorised by gender, ethnicity, and language spoken. All focus groups were audio-taped and transcribed verbatim, with subsequent translation into English for groups conducted in other languages. Data analysis was performed by combining the key elements of grounded theory and content analysis with the assistance of the qualitative software ATLAS/ti 5.0. RESULTS: Five domains (pain, physical disability, other symptoms of OA, mental health, and social health) were identified from the 74 items reported as important by at least one subject. These domains were important for subjects from all ethnic groups with the exception of social health, which was more often important for Malay subjects. Items more commonly reported as important in the pain, physical disability, and other symptoms of OA domains were generally similar across ethnic groups, In contrast, important items in the mental and social health domains differed among ethnic groups. CONCLUSIONS: The impact of knee OA on HRQoL is broadly similar in both Asian and Western socio-cultural contexts. Both similarities and differences in important domains and items were identified among subjects with knee OA from 3 major Asian ethnic groups.