Recent years have seen a dramatic increase in the number of clinical trials investigating the potential efficacy of medicinal cannabinoids for the symptomatic treatment of chronic pain and spasticity in multiple sclerosis (MS). A number of different cannabinoids have been used, including: Δ9-tetrahydrocannabinol (THC) itself; the synthetic Δ9-THC, dronabinol; a 1:1 ratio of Δ9-THC:cannabidiol (Sativex^®); and the synthetic Δ9-THC metabolites CT-3 and nabilone. Other Cannabis extracts have also been tested. While 2–3 years ago there was little consensus in the literature, now the majority of studies are beginning to suggest that cannabinoids are useful in the treatment of MS in at least a subset of individuals. Their adverse side-effect profile has generally been mild compared with other drugs used for pain and spasticity; nonetheless, there is still concern about potential long-term side effects, particularly psychiatric side effects and effects on fetal development.