16 patients with pain due to diabetic peripheral neuropathy were randomly assigned to inhale either high dose, medium dose, low dose (7%, 4%, 1% by weight, respectively) of delta-9-tetrahydrocannabinol (THC), or placebo at the beginning each treatment session. The study consists of four 2-week treatment sessions, where participants received treatment at the beginning and used the remaining 2 weeks as a washout period. Patients were assessed on spontaneous pain, evoked pain, cognitive testing, and subjective highness over time (within 4 hours post-treatment). Treatment with THC demonstrated a significant dose-dependent reduction in both spontaneous and evoked pain intensity and a moderate disturbance to cognition.