Abstract Background: Studies of weight and health-related quality of life (HRQOL) generally focus on white populations. This analysis examines the association between clinical weight categories and physical HRQOL in five racial/ethnic groups of older women and determines the extent to which emotional/psychological (social support, caregiver burden) and physical health (diabetes, osteoarthritis) factors modify this relationship. Methods: The cross-sectional analysis, completed in 2007, used baseline data from postmenopausal women enrolled in the Women's Health Initiative (WHI) during the 5-year recruitment period (1993-1998). Results: Of 161,393 women, 83% were non-Hispanic white, 9% were African American, 4% were Hispanic/Latina, 3% were Asian/Pacific Islander, and /=30 kg/m(2)) was most common in non-Asian minority groups. Regression modeling showed higher odds of poor physical HRQOL with increasing weight category in all groups. In the total sample, these odds were at least 6 times as high in women with class 3 obesity as in women of normal weight and were only mildly attenuated after the analysis adjusted for emotional/psychological factors. Further adjustment for physical health factors made odds ratio (OR) estimates drop from 2.36 to 1.59 for class 1 obesity and from 6.96 to 3.71 for class 3 obesity. This pattern generally persisted within each racial/ethnic group. Conclusions: Heavier weight negatively affects physical HRQOL in postmenopausal women across diverse racial/ethnic backgrounds. Weight-relevant physical health factors have a greater impact on this weight-HRQOL association than do emotional/psychological factors.