The present invention relates to the use of cannabidiol (CBD) in the treatment of Angelman syndrome (AS). CBD has been shown to be particularly effective in improving anxiety in rodent models of AS. The CBD is preferably substantially pure. It may take 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) and the other components of the extract are characterised. Alternatively, the CBD is synthetically produced. Alternatively, the CBD may be used as a botanical drug substance (BDS) from a cannabis plant in which CBD is the predominant cannabinoid. The CBD may also be present in combination with other cannabinoids and non-cannabinoid components such as terpenes. In use the CBD may be used concomitantly with one or more other medicaments. Alternatively, the CBD may be formulated for administration separately, sequentially or simultaneously with one or more medicaments or the combination may be provided in a single dosage form. Where the CBD is formulated for administration separately, sequentially or simultaneously it may be provided as a kit or together with instructions to administer the one or more components in the manner indicated. It may also be used as the sole medication, i.e. as a monotherapy.
