This study researches the physiological and biochemical effects of long-term work with fuel-related pollutants among the personnel of filling stations at Mosul with gasoline. This goal will be realized through the investigation of important biomarkers, such as liver enzymes (ALT, AST), serum albumin, creatinine, and lead levels, which will help evaluate the presence of a toxicological burden at an early stage. The sample consisted of 100 exposed workers which were divided on intervals of daily shift (18-hours and 8-hours), and contrasted with 30 non-exposed (healthy, non-smoking male) subjects. Quantification of enzymatic activity and biochemical levels was performed upon blood serum samples with the help of validated colorimetric assays. Duncan multiple range test was applied to predict the statistical significance at P 0.05. The findings indicated a remarkable increase in the level of ALT, albumin, creatinine and lead in the serum of exposed, workers than in the controls. Although the level of AST also went up, it did not reveal any statistically significant difference. A dose-dependency pattern was observed between the work periods and toxic biomarkers.