This review will introduce petrol (gasoline) sniffing as a specific form of substance abuse. Petrol sniffing is associated with dysfunctions that range in severity from subtle cognitive impairment to encephalopathy and death, and these are discussed with respect to their specific neurological and cognitive bases. Morbidity and mortality rates will also be presented that suggest severe central nervous system damage occurs as a result of petrol sniffing. The neuropharmacological actions of tetraethyl lead and volatile hydrocarbons, the components within petrol, and their contributions to the effects of sniffing petrol are investigated. Reports of human occupational or recreational exposure to either lead additives or volatile hydrocarbons (i.e. inhalants) have provided evidence of the neurological and cognitive effects that may also occur with petrol sniffing. Petrol sniffing causes a progressive decline of cognitive function that eventually leads to permanent neurological changes.