The current study aimed to investigate the impact of long-term exposure to sub-lethal concentrations of benzene on the biochemical and hematological parameters of grass carp Ctenopharyngodon idellus. Eighty healthy fish were randomly divided into four treatment groups: T1 (control group), T2, T3, and T4, with each exposed to different levels of benzene concentrations (0, 0.25, 0.5, and 0.75ppm) for a period of 96h. The biochemical parameters including glucose and total protein were measured, as well as the hematological parameters, including erythrocytes and leukocyte counts, lymphocytes, neutrophils, hemoglobin (Hb) content, and packed cell volume (PCV). The results showed that there were significant decreases (P≤ 0.05) in the total number of erythrocytes and glucose levels in the treatments (T2, T3, and T4) compared to the control group (T1). It was also noted that there were significant decreases (P≤ 0.05) in the total number of leukocytes and lymphocytes between T3 and T4 groups with the T1 group. No significant differences (P> 0.05) were observed in PCV, total protein, and neutrophils among the treatments (T2, T3, and T4) when compared to the T1 group. As for blood Hb, significant decreases (P≤ 0.05) were found between T4 and T1 groups. It was deduced that exposure to sub-lethal concentrations of benzene can severely affect the biochemical and hematological parameters of grass carp, thereby affecting their physiological status.