Cannabinoids are well known for their effects on neurotransmission in the central nervous system. Whereas the components of cannabinoid signaling have been intensively studied in neurons, recent data suggest that a cannabinoid signaling system, i.e. the endogenous cannabinoid ligands, the receptors that they activate and the components that degrade them, also exist in the non-neuronal cells of the brain, the glia. Because of their abundance and because of their importance in maintaining brain homeostasis, glial cells are involved in and affected by virtually all neurological diseases. Interestingly, a lot of neurological conditions, chronic and acute, are associated with a disturbance of the endocannabinoid system. This raises the possibility that effects of cannabinoids on glial cells have an important impact in these conditions and could potentially be exploited therapeutically. Cannabinoids regulate various physiological functions of glial cells, such as glucose metabolism and gap junction permeability and also have a major influence on pathophysiological functions of glial cells, like migration, cytokine production and nitric oxide release. In this review we summarize the current knowledge about cannabinoids and glial cells with a special focus on neurological conditions, especially neurodegenerative, demyelinating and neoplastic diseases.