To see whether the percentage of older adults entering substance abuse treatment for their first time was increasing and whether there were changes in the use patterns leading to the treatment episode, particularly an increase in illicit drugs.The Treatment Episode Data Sets publicly available from the Substance Abuse Mental Health Services Administration from 1998 to 2008.Young adults age 30-54 years as a comparison group (N = 3,547,733) and those age 55 years or older (N = 258,542) with a first-time admission for a publicly funded substance abuse treatment.Demographic and substance use history variables at admission.The proportion of older adults going for substance abuse treatment for the first time is increasing relative to younger adults. The pattern of drug use is also changing, with an increasing illicit drug involvement (cocaine and heroin) in older adult admissions.We know little of these long-time users, their current medical state, cognitive abilities, and psychiatric symptoms after such a long exposure time. Previous studies on heroin and cocaine exposure focused on individuals identified much earlier in life, and the aging long-term users might represent a relatively large but unknown population.