OBJECTIVES: To assess the contribution of the Zarit score, a measure of perceived caregiver burden in Alzheimer's disease, to health related quality of life as measured by the physical and mental component scores of the SF-12 instrument and SF-6D health utilities. METHODS: A survey of Alzheimer caregivers was undertaken in the US in 2009 (n = 1,079). This survey captured both the characteristics of caregivers and the characteristics of the patient to whom the caregiver gave most attention. At the same time, caregivers were asked to complete the Zarit burden of care questionnaire and the SF-12 HRQoL instrument. To assess the impact of Zarit scores on HRQoL, linear regression (ordinary least squares) models were specified and estimated for the physical and mental component summary scores of the SF-12 and the health utility scores from the SF-6D.  Independent variables included: caregiver and patient characteristics. RESULTS: Average PCS and MCS scores were 47.7 (STD 11.17) and 42.5 (STD 11.93) respectively; utility score was 0.68 (STD 0.13). Zarit scores were distributed with 20.4% of respondents reporting a minimal or no burden, 37.7% a mild to moderate burden, 33.1% moderate to severe burden and 8.8% a severe burden. Overall16.3% were judged to have mild AD, 53.7% moderate and 30.0% severe.  Zarit scores played the key role with their greatest impact on the MCS rather than the PCS dimensions of the SF-12. In the severe AD category the PCS deficit is -5.65 (t= -4.23) compared to a deficit of -17.94 (t= -14.09) for MCS. The corresponding health utility deficit is -0.19 (t= -13.15). Other key variables are caregiver age and gender, patient age and gender and living situation. CONCLUSIONS: Perceived caregiver burden is associated primarily with deficits on the mental component scores of the SF-12 and on SF-6D health utilities.