Abstract A large proportion of patients with multiple sclerosis (MS) have spasticity, which has a marked impact on their quality of life. Anecdotal evidence suggests a beneficial effect of cannabis on spasticity as well as pain. Recently, randomized, double-blind, placebo-controlled studies have confirmed the clinical efficacy of cannabinoids for the treatment of spasticity in patients with MS. Based on these data, nabiximols (Sativex), a 1:1 mix of Δ-9-tetrahydrocannabinol and cannabidiol extracted from cloned Cannabis sativa chemovars, received approval for treating MS-related spasticity in various countries around the globe. In this article we review the current understanding of cannabinoid biology and the value of cannabinoids as a...