The psychometric properties of the Brief Pain Inventory (BPI), a widely used measure of pain and its impact on functioning, were assessed using data from two clinical trials of controlled-release oxycodone in osteoarthritis (OA) patients. Specifically, the pain-related functional interference subscale and the sleep item from that subscale were examined. In Study 1 (n = 133), '' night awakenings with pain '' was positively correlated with the BPI interference score and sleep item and both correlated negatively with '' quality of sleep. '' In Study 2 (n = 107), pain experienced '' at night while in bed '' correlated higher with sleep interference than with the BPI interference subscale. Intraclass correlations denoted adequate test-retest reliability; moderate-to-large Guyatt's statistics provided evidence of responsiveness. These analyses address a gap in the literature regarding the psychometric properties of the BPI interference measures in noncancer pain patients, confirming their reliability, validity, and responsiveness as potential endpoints in trials of pain medications involving patients with OA.