The use of the cannabinoid cannabidiol (CBD) in the treatment of Sturge Weber syndrome. The invention is particularly directed to reducing either seizure ornon-seizure symptoms in patients suffering with Sturge Weber syndrome. Cannabidiol may be used in combination with one or more concomitant anti-epileptic drugs for the treatment of Sturge Weber syndrome. In some instances the CBD used is in the form of a highly purified extract of cannabis such that the CBD is present at greater than 98% of the total extract (w/w). In some cases the cannabinoid tetrahydrocannabinol (THC) has been substantially removed, to a level of not more than 0.15% (w/w) and the propyl analogue of CBD, cannabidivarin, (CBDV) is present in amounts of up to 1%. Alternatively, the CBD may be a synthetically produced CBD.