CONTEXT: Although opioids are increasingly used for chronic noncancer pain (CNCP), we know little about opioid dosing patterns among individuals with CNCP in usual care settings, and how these are changing over time. OBJECTIVES: To investigate the distribution of mean daily dose and mean days supply among patients with CNCP in two disparate populations, one national and commercially insured population (HealthCore) and one state based and publicly insured (Arkansas Medicaid), for years 2000 and 2005. METHODS: For individuals with any opioid use, we calculated the distribution of mean daily dose (in milligram morphine equivalents), mean days supply in a year, mean annual dose, and patient characteristics associated with heavy utilizers of opioids. RESULTS: Between 2000 and 2005, across all percentiles, there was little change in the mean daily opioid dose. In HealthCore, mean days supply increased most rapidly at the top end of the days supply distribution, whereas in Arkansas Medicaid, the greatest increases were near the median of days supply. In HealthCore, the top 5% of users accounted for 70% of total use (measured in milligram morphine equivalents), and the top 5% of Arkansas Medicaid users accounted for 48% of total use. The likelihood of heavy opioid utilization was increased among individuals with multiple pain conditions, and in HealthCore, among those with mental health and substance use disorders. CONCLUSION: Opioid use is heavily concentrated among a small percent of patients. The characteristics of these high utilizers need to be further established, and the benefits and risks of their treatment evaluated.