The indiscriminate use of herbicides has led to the contamination of water bodies, possibly affecting the health of aquatic biota, especially fish. Atrazine is considered as toxicants for aquatic fauna, due to its high persistence in soil, high half-life and high mobility toward aquatic bodies as well as high solubility in water. The objective of the present study was to determine (LC 50 ) and to evaluate the acute and chronic toxicity of atrazine on the biochemical parameters; total protein and serum albumin of freshwater grass carp (Ctenopharyngodon idella). Above 15 μlL -1