Abstract: The health concerns for petroleum workers warranted this study in asymptomatic exposed (n=64) and control (n=64) groups. The serum activity (IU L–1) in the exposed group for alanine amino transferase, ALT (49.25±5.28), aspartate amino transferase, AST (68.23±6.95), alkaline phosphatase, ALP (59.23±7.21) and gamma glutamyl transpeptidase, GGT (36.06±6.99) was comparatively higher (p<0.05) than that in the control (21.56±7.68, 47.89±7.14, 29.53±6.31 and 18.11±4.00, respectively) by 128.43, 42.47, 100.58 and 99.12%. The serum concentration for total bilirubin, TB (22.89±6.78 μmol L–1) and conjugated bilirubin, CB (17.65±4.77 μmol L–1) in the exposed group was higher (p<0.05) than that in the control group (11.59±2.10 and 7.53±1.71 μmol L–1) by 97.50 and 134.40%, respectively whereas the computed TB:CB ratio (1.30±1.62) was lower (p<0.05) than that in the control group (1.54±2.33) by 15.58%. Aside the AST:ALT ratio (1.39±1.26) that was lower (p<0.05) than that in the control (2.22±1.84) by 37.39%, the other observations in the exposed group for computed serum ALT:AST ratio (0.72±2.42), ALT:ALP ratio (0.83±2.33) and CB:TB ratio (0.77±2.72) were higher (p<0.05) than that in the control (0.45±3.45, 0.73±2.04 and 0.65±3.11) by 60.00, 13.70 and 18.46%, respectively. The study suggests dysfunctional liver and other organs, with the attendant health implications in the petroleum depot workers, highlighting the need for health caution and protection.