We report on the development and validation of an instrument to assess discordance between physicians and their patients on evaluations of health-related information: the Patient-Physician Discordance Scale (PPDS). The 10-item questionnaire is designed to be employed across chronic diseases and can be used in clinical practice and research. It measures the extent of patient-physician discordance on five aspects of the patient's health status and five aspects of the office visit. A prospective study with 200 outpatients with inflammatory bowel disease and their treating physicians revealed that the 10-item discordance scores had good construct validity and satisfactory convergent validity. Overall discordance and the three subscales, discordance on symptoms and treatment, well-being, and communication and satisfaction, identified by factor analysis, had acceptable internal consistency. Patient and physician ratings demonstrated moderate-to-high concurrent validity. Study limitations and directions for future research with PPDS are discussed.