This study was conducted to investigate acute toxic effects of spinosad on Glutathibne-related oxidative stress markers, lipid peroxidation, heat shock proteins, apoptosis in the liver of Oreochromis niloticus selected as a model organism. The fish were exposed to sublethal spinosad concentrations (25, 50, 75 mg/L) for 24-48-72 h. tGSH, GSH, GSSG, and TBARS contents, GSH/GSSG ratio, and GPx, GR, GST and caspase enzyme activities were measured using spectrophotometrical methods, and Hsp70 content was measured by ELISA technique. The results demonstrated that spinosad exposure caused significant alterations in the GSH-related oxidative stress markers, and also caused increases in lipid peroxidation and stress proteins with inducing ROS generation in the liver. Apoptosis initiated with the induction of caspase-3 and Hsp70 could not protect the liver cells. Our results indicated that GSH-related antioxidant system tried to protect the liver cells from spinosad-induced hepatotoxicity however, the oxidative stress resulting from induction of ROS generation induced apoptosis in the liver of O. niloticus. (C) 2013 Elsevier B.V. All rights reserved.