Introduction: Benzene is an important raw material for the manufacture of synthetic rubbers, gums, lubricants, dyes, pharmaceutics and agriculture chemicals. Occupational exposure to Benzene may induce some adverse health effects. Aim of the work: This study aimed to the evaluation of Benzene exposure among petrol Stations workers by
assessment of some symptomatic, hematological and immunological changes by using trans- trans muconic acid (t, t MA) as a urinary indicator. Subjects and Methods: A comparative cross – sectional study was conducted on five petrol stations. The study sample was 32 workers, they were classified as 12 exposed to benzene and 20 non-exposed control group. All subjects were interviewed and subjected to a structured questionnaire. They were asked to pass urine at the end of theshift to determine trans, trans muconic acid using high performance liquid chromatography (HPLC). Blood samples had obtained from all volunteers to detect peripheral blood mononuclear cells (PBMC) also serum concentrations of IgG and IgM were determined by suitable method. Results: A statistically significant higher prevalence of adverse symptoms among exposed workers compared to control group. In addition, there were significantly higher values of trans, trans muconic acid among exposed group  compared to control group with significant correlation (P< 0.01) between t, t MA level and duration of exposure. Conclusion: Exposure to benzene in Petrol stations workers induces significant reduction in peripheral blood mononuclear cells (PBMC), immunological changes, and adverse symptomatic effects.
Recommendations: More studies are needed to explore the details of occupational exposure to benzene for purposes of prevention and control.