The possibility that chronic abuse of volatile substances can cause permanent neurological, psychiatric, and intellectual sequelae is critically reviewed. Toluene, present in the commonly used adhesives, is most often implicated in 'glue sniffing'; this review focuses on its potential long-term effects. Many criticisms--particularly poor matching of control samples and inability to distinguish between acute and chronic effects--can be levelled at the available studies, while no adequate follow-up studies have been performed. In the light of present knowledge, the possibility that permanent structural brain damage, with accompanying psychiatric manifestations, results from solvent abuse remains inconclusive.