The Brief Pain Inventory short form (BPI-sf) is a validated, widely used, self-administered questionnaire developed to assess the severity of pain and the impact of pain on daily functions. A modified version was used daily in randomised control trials of patients with arthritis undergoing treatment with cyclooxygenase-2 specific inhibitors and non-steroidal anti-inflammatory drugs. Results indicate that the modified BPI-sf, much like the original scale, was internally reliable, consistent over time, and had good construct, as well as convergent and predictive validity in assessment of patients suffering from conditions of chronic pain. Each scale and individual pain intensity item refers to changes in osteoarthritis pain associated with medication use. The modified BPI-sf, like the parent scale, is a valid and reliable tool for situations in which pain is assessed daily and minimises the burden placed on patients to record information necessary for scientific investigations.