This invention relates to a pharmaceutical composition comprising or consisting essentially of the phytocannabinoids cannabidivarin (CBDV) and cannabidiol (CBD). The composition is particularly safe and efficacious for use in the treatment of neurological conditions, characterized by hyper-excitability of the central nervous system, convulsions or seizures such as occur in epilepsy. Preferably the CBDV and the CBD are present with at least one non-cannabinoid component of cannabis such as one or more terpenes or a terpene fraction. More particularly the composition further comprises one or more cannabichromene type compounds. Particularly cannabichromene propyl variant (CBCV) and/or cannabichromene (CBC). More particularly still the composition is absent or substantially absent of other cannabinoids, including in particular tetrahydrocannabinol (THC) and tetrahydrocannabivarin (THCV), which would normally be present in significant amounts in cannabis chemotypes bred to contain a significant amount of CBDV and/or CBD.