Before being introduced for widespread use, health status instruments should be evaluated for reliability, validity, and responsiveness to relevant clinical changes. In a previous study the validity and reliability of Aquarel, a disease-specific quality-of-life (QOL) questionnaire for pacemaker patients, were tested and found satisfactory. The purpose of this study was to assess the sensitivity to change in health of Aquarel. A cohort of 51 patients was assessed at baseline and at 4-6 weeks after pacemaker implantation. We compared the sensitivity to change over time on the Aquarel scores to the scores on the SF-36 using various techniques (t-test value, effect size, standard error of measurement). Using the 1-standard error of measurement (SEM) criterion for clinically relevant change, Aquarel seemed to provide better classification of patients compared to the SF-36 alone. This study supports the value of Aquarel as a disease-specific measure of QOL in pacemaker patients.