BACKGROUND: the evaluation of the determinants of change over time in health-related quality of life (HR-QoL) in older people is limited. This study aims to identify patterns of change in HR-QoL over 7 years and their determinants using data from the British Women's Heart and Health Study, a representative sample of older women (n = 4286). METHODS: longitudinal latent class analysis was used to identify subpopulations of women with similar HR-QoL trajectories from 1999-2000 to 2007. HR-QoL was measured using the EQ-5D. Multivariate multinomial logistic regression was used to model the association of identified trajectories with baseline predictors after multiple imputation of missing data. RESULTS: four distinct EQ-5D trajectories were suggested: high (19% of women), high decline (22%), intermediate (42%) and low decline (16%). Prevalent arthritis (OR = 13.4; 95% CI: 8.8, 20.5), diabetes (OR = 4.6; 95% CI: 1.5, 14.2) and obesity (OR = 3.9; 95% CI: 2.5, 6.0) were the strongest predicting health conditions of adverse changes in HR-QoL and physical activity the strongest predicting lifestyle factor (OR = 2.8; 95% CI: 2.0, 3.9). CONCLUSIONS: findings suggest that older women without obesity or pre-existing health conditions who undertake more physical activity are more likely to experience high HR-QoL, reinforcing the importance of these factors for healthy ageing.