Michael Von Korff and colleagues at the Center for Health Studies, Group Health Cooperative (GHC) of Puget Sound created a measure of chronic disease status (CDS) using automated outpatient pharmacy data. They reported the measure appeared to provide a stable and valid measure of health status. The availability of such a measure could become a new tool for a variety of applications, including screening, resource allocation, and quality assurance. The measure was replicated for its reliability and construct and predictive validity in the KPNW membership using automated pharmacy data. Reliability and validity were tested using correlation and regression techniques. The CDS showed test-retest reliability over time. It showed construct validity with the RAND-36 instrument and the BSI-8 depression screener. It showed predictive validity with health care visits and hospitalizations. The results were similar to those at GHC. The findings indicated that the CDS can serve, with certain precautions, as a readily accessible low cost measure of health status.