30 patients with chronic pain took placebo, 10 mg or 20 mg oral dronabinol at 3 sessions in a randomly allocated sequence. They were compared to 20 patients without chronic pain who smoked a 1.99% and 3.51% THC marijuana cigarette at each session. Both groups were given the Addiction Research Center Inventory to determine whether oral dronabinol and smoked cannabis have similar psychoactive effects. Results indicated that oral dronabinol and smoked cannabis had similar psychoactive effects, but the effects of dronabinol peaked at 2 hours, while the effects of smoked cannabis peaked at 30 minutes. Both drugs had significant differences in ARCI score compared to placebo.