Please cite this article as: Geng, X., Shao, H., Zhang, Z., Ng, J.C., Peng, C.,Malathioninduced testicular toxicity is associated with spermatogenic apoptosis and alterations in testicular enzymes and hormone levels in male Wistar rats, Environmental Toxicology and Pharmacology (2015), http://dx.doi.org/10. 1016/j.etap.2015.01.010 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Malathion caused the reduction in the sperm counts and motility. The reduced body and testis weights were coupled with mild to severe degenerative changes in seminiferous tubules. We Page 3 of 32 A c c e p t e d M a n u s c r i p t 3 found malathion at 54 mg/kg increased spermatogenic apoptosis rate which was confirmed by changes in protein expression of Bax and Bcl-2. The activities of testicular enzymes including ACP, LDH and γ-GT were significantly altered with the reduced level of reproductive hormones such LH, FSH and T. These results indicate that malathion can elicit deleterious effects on reproductive system of rats. The abnormal levels of hormones and apoptotic proteins induced by malthion may play important roles.