['Increased attention to improving the provision of analgesia has led to calls for increased use of pain measurement systems, including visual analog scales, which have not been validated for use in clinical care.', 'To evaluate the ability of the visual analog scale to differentiate between patients with acute, painful conditions requiring pain medication, and those not requiring analgesia.', 'This was a prospective, observational study of a convenience sample of patients with acute pain. Subjects were asked about their desire for medication. Visual analog scale pain scores were determined.', 'One hundred four patients participated. Patients requesting pain medication had a mean visual analog scale score of 66. The mean score for those not requesting medication was 45. The difference between the means was 21 [95% confidence interval (95% CI) for difference between the means was 10.7]. The area under the receiver operating characteristic curve for the visual analog scale was 0.72 (95% CI = 0.61 to 0.82).'] Do visual analog pain scores define desire for analgesia in patients with acute pain?