OxyContin (Purdue Pharma L.P., Stamford, Conn) was approved by the Food and Drug Administration (FDA) in 1995 as a sustained-release preparation of oxycodone hydrochloride and was thought to have much lower abuse potential than immediate-release oxycodone because of its slow-release properties. However, beginning in 2000, widespread reports of OxyContin abuse surfaced. In response, Purdue Pharma L.P. sponsored the development of a proactive abuse surveillance program, named the Researched Abuse, Diversion and Addiction-Related Surveillance (RADARS) system. In this paper, we describe results obtained from one aspect of RADARS--the use of drug abuse experts (ie, key informants)--as a source of data on the prevalence and magnitude of abuse of prescription drugs. The results indicate that prescription drug abuse has become prevalent, with cases reported in 60% of the zip codes surveyed. The prevalence of abuse was rank ordered as follows: OxyContin >or= hydrocodone > other oxycodone > methadone > morphine > hydromorphone > fentanyl > buprenorphine. In terms of the magnitude of abuse (>or=5 cases/100,000 persons in a 3-digit zip code), modest growth was seen with all analgesics over the 10 calendar quarters we monitored, but was most pronounced with OxyContin and hydrocodone. These results indicate that OxyContin abuse is a pervasive problem in this country, but that it needs to be considered in the context of a general pattern of increasing prescription drug abuse. Over the past 5 years, there have been reports, frequently anecdotal, that opioid analgesic abuse has evolved into a national epidemic. In this study, we report systematic data to indicate that opioid analgesic abuse has in fact increased among street and recreational drug users, with OxyContin and hydrocodone products the most frequently abused. Steps need to be taken to reduce prescription drug abuse, but very great care needs to be exercised in the nature of these actions so the legitimate and appropriate use of these drugs in the treatment of pain is not compromised as a result.