Gap junctions are intercellular channels which directly connect the cytoplasm between neighboring cells. In the central nervous system (CNS) various kinds of cells are coupled by gap junctions, which play an important role in maintaining normal function. Neuronal gap junctions are involved in electrical coupling and may also contribute to the recovery of function after cell injury. Astrocytes are involved in the pathology of most neuronal disorders, including brain ischemia, Alzheimer's disease and epilepsy. In the pathology of brain tumors, gap junctions may be related to the degree of malignancy and metastasis. However, the role of connexins, gap junctions and hemichannels in the pathology of the diseases in the CNS is still ambiguous. Of increasing importance is the unraveling of the function of gap junctions in the neural cell network, involving neurons, astrocytes, microglia and oligodendrocytes. A better understanding of the role of gap junctions may contribute to the development of new therapeutic approaches to treating diseases of the CNS.