This is a collaborative study comparing the quality of life (QoL) and its predictors between outpatients of university teaching hospitals in southwest China and southern Thailand in terms of different domains of QoL as well as whether socio-economic variables affect the QoL of the two groups of patients to the same extent. Two hundred sixty-one and two hundred forty-eight randomly chosen outpatients were recruited at Chinese and Thai hospitals, respectively, and were interviewed using the SF-36 scale. The QoL of the Chinese patients had a higher adjusted score for 'physical functioning', but the scores for 'role limitations attributed to physical problems and emotional problems' were higher in the Thai patients. Multiple regression analysis showed that sex, marital status, education, family income and residency were predictors of the total QoL score. Age and area had significant interactions with 'country' in the general health domain.