OBJECTIVE: To determine the validity and sensitivity to change of the Work Productivity Questionnaire (WPQ) in a large, national sample of participants in the Multicenter Assessment of Transdermal Therapy in Overactive Bladder with Oxybutynin (MATRIX). METHODS: The WPQ is an 8-item subset of the Work Limitations Questionnaire (WLQ) which measures the degree to which health problems interfere with ability to perform job roles. The WPQ includes physical, mental (concentration), time (interruptions and adherence to schedule) and output (ability to handle workload) scales and a WPQ Index is computed to estimate overall productivity loss. In MATRIX, WPQ scores were compared to the King's Health Questionnaire (KHQ), a validated OAB-specific quality of life (QOL) instrument. We examined the relationship between WPQ scores and conceptually-related KHQ domains at baseline, and the sensitivity of the WPQ to change in related KHQ measures at 3 months. RESULTS: A total of 1112 employed OAB patients were enrolled in MATRIX, from 327 US sites. The number of responses available for each scale at baseline were: time (n=830, 75%); physical (n=866, 78%); mental (n=818, 74%); output (n=814, 73%). A WPQ Index was computable for 740 participants. Spearman correlations between the KHQ physical limitations domain and the WPQ physical scale was 0.297, and between the KHQ role limitations and WPQ index score was 0.356. The WPQ appears to be sensitive to change over time, with WPQ physical scale scores and KHQ physical limitations score both decreasing at three months and the WPQ Index and KHQ role limitations also both decreasing at three months. CONCLUSION: Results suggest that the WPQ is a valid measure of work productivity in patients with OAB.