The purpose of this study was to assess a patient specific measure for eliciting and recording patients' problems. While the notion was to develop a measure that would be applicable to a number of conditions or disabilities, this study assessed the measure's performance on 63 out-patients with mechanical low back pain. Patients were asked to identify up to five important activities they were having difficulty with as a result of their back pain. Patients rated difficulty on an 11-point numerical scale. At subsequent reassessments patients were informed of the activities and corresponding difficulty scores identified at the previous assessment and asked to provide a current difficulty score. Concurrent validity of the patient-specific measure was assessed using the Roland-Morris Questionnaire. Sensitivity to valid change over time was determined by comparing the measure's score to the average patient/clinician global rating of change. Moderate to excellent reliability, validity, and sensitivity to change coefficients were obtained for the patient-specific measure, suggesting it may be a useful tool in clinical practice.