OBJECTIVE: To report trends and characteristics of long-term opioid use for non-cancer pain. METHODS: CONSORT (CONsortium to Study Opioid Risks and Trends) includes adult enrollees of two health plans serving over 1 per cent of the US population. Using automated data, we constructed episodes of opioid use between 1997 and 2005. We estimated age-sex standardized rates of opioid use episodes beginning in each year (incident) and on-going in each year (prevalent), and the per cent change in rates annualized (PCA) over the 9-year period. Long-term episodes were defined as > 90 days with 120+ days supply or 10+ opioid prescriptions in a given year. RESULTS: Over the study period, incident long-term use increased from 8.5 to 12.1 per 1000 at Group Health (GH) (6.0% PCA), and 6.3 to 8.6 per 1000 at Kaiser Permanente of Northern California (KPNC) (5.5% PCA). Prevalent long-term use doubled from 23.9 to 46.8 per 1000 at GH (8.5% PCA), and 21.5 to 39.2 per 1000 at KPNC (8.1% PCA). Non-Schedule II opioids were the most commonly used opioid among patients engaged in long-term opioid therapy, particularly at KPNC. Long-term use of Schedule II opioids also increased substantially at both health plans. Among prevalent long-term users in 2005, 28.6% at GH and 30.2% at KPNC were also regular users of sedative hypnotics. CONCLUSION: Long-term opioid therapy for non-cancer pain is increasingly prevalent, but the benefits and risks associated with such therapy are inadequately understood. Concurrent use of opioids and sedative-hypnotics was unexpectedly common and deserves further study.