There are wide ranging effects of alcohol on the nervous system. Some interfere with physiological and neurochemical functions but ultimately structural damage occurs. During life one of the most impressive changes is brain shrinkage which can be visualized using neuroradiological imaging techniques. This article reviews the pathological explanations for brain shrinkage and addresses the question of the pathogenesis of the reversible component of this damage in relation to prolonged abstinence from alcohol. This shrinkage seems to relate to a loss of white matter. However, the cortex is also abnormal in that there is a loss of neurones from the frontal region. In this and other regions of the cortex examined there is shrinkage of the neuronal soma. This is reflected in a retraction of the neuronal dendritic arbor which plays a crucial role in cell-to-cell communication. In addition, the cerebellum appears to be vulnerable in alcoholic patients although it may well be that associated nutritional deficiencies play an important role. The Wernicke-Korsakoff syndrome is another important deficiency disorder which is seen most frequently in alcoholic patients. Two important population groups which are considered in this review are females and moderate ('social') drinkers. Females are thought to be more susceptible to the damaging effects of alcohol than males and this is examined in the light of the scant data available. Similarly, there are few neuropathological data on people who drink 30-80 grams of alcohol per day. In order to assess so-called 'safe levels of drinking' this is an important group to study.