OBJECTIVES: To study the longitudinal trend (between 2000 and 2012) in substance use admissions among older adults, i.e., those aged 55 or older. METHODS: Using the Treatment Episode Data Set - Admissions (TEDS-A) for the period between 2000 and 2012, we analyzed the trend in substance use admissions reported for older adults. Substance use admissions for older adults as a proportion of total substance use admissions were compared.  Also, the trend in admission for primary substances such as cocaine/crack, marijuana/hashish, heroin, non-prescription methadone, other opiates and synthetics, methamphetamine, and benzodiazepines was compared. RESULTS: Of the total admissions for substance use in 2000, 3.4 percent were attributable to older adults.  Over time, there was a increase in this proportion and in 2012, 7.0 percent of all substance use admissions were accounted for by older adults.  Older adults also exhibited sharp escalation in proportion of admissions between 2000-2012 where primary substance that led to admission was cocaine/crack (63% increase), marijuana/hashish (150% increase ), heroin (26% increase), non-prescription methadone (200% increase), other opiates and synthetics (221% increase), methamphetamine (275% increase), and benzodiazepines (67% increase). CONCLUSIONS: It is important to note that though the total number of substance use admissions between 2000 and 2012 changed only a little, the proportion of admissions attributable to older adults increased greatly. Among older adults, substance use is an important psychosocial co-comorbidity.  Admissions for certain types of substances appear to be on the rise . Presence of substance use translates into treatment need. It can affect health outcomes and complicate management of other co-morbid conditions. Therefore, a surge in substance use in older persons coupled with aging of the US population has substantial implications for the entire healthcare system. There is an urgent need for appropriate preventive and treatment polices aimed specifically towards older adults with a substance use disorder.