Glue and thinner sniffing is a serious medical problem since the volatile constituents of these substances can lead to severe damage to bone marrow, liver, kidney, brain, and heart. The exact mechanisms responsible for tissue and organ damage in children with inhalant abuse have not yet been determined. In this study, we aimed to determine the levels of antioxidant enzymes and malondialdehyde in children with inhalant abuse. Erythrocyte and plasma glutathione peroxidase (GSH-Px) activities, erythrocyte superoxide dismutase (SOD) activity, and erythrocyte and plasma malondialdehyde (MDA) levels were measured as biological markers of oxidative damage and lipid peroxidation in 37 glue and thinner (inhalant) abusers. The levels were compared with those of the 27 well-matched healthy adolescents. Erythrocyte SOD activity and erythrocyte and plasma MDA levels were significantly higher, whereas erythrocyte and plasma GSH-Px activities were significantly lower in children with inhalant abuse when compared to controls (p<0.01). These findings imply that chronic inhalation of volatile substances can alter the levels of antioxidant enzymes including SOD and GSH-Px, and can increase lipid peroxidation in adolescent abusers.