Background: Studies show that there is association between air pollution and disturbances on normal function of various systems of body. The main aim of this study was to determine the effects of diesel oil vapor inhalation on serum creatine, alkaline phosphatase, SGOT and SGPT levels as indices of liver function in male rats.Methods: Thirty two rats were randomly divided into 4 groups: control and three treatment groups that exposed to diesel oil vapor for 1 hour/day, for 2 hours/day and for 3 hours/day. After a period of 6 weeks, blood samples were collected and investigated. Serum level of alkaline phosphatase, creatine, glutamate oxaloacetate transaminase (SGOT) and glutamate pyruvate transaminase (SGPT) were measured by spectrophotometry method. Results: Our findings indicated that there was no significant difference between serum alkaline level of control and experimental rats. Serum creatine level was significantly increased in rats exposed to diesel oil for 1hour/day, 2h/day and 3h/day (P<0.001, P<0.01 and P<0.001, respectively). Also, SGOT was significantly decreased in rats exposed to diesel oil for 2h/day and 3h/day (P<0.01 and P<0.05, respectively). SGPT was non-significantly decreased in rats exposed to diesel oil vapor compared with control animals. Conclusions: We have shown that exposure to diesel oil vapor can bring about enhanced kinase level, decreased SGPT level indicating the health risk caused by exposure to diesel oil inhalation, in particular, to liver.Background: Studies show that there is association between air pollution and disturbances on normal function of various systems of body. The main aim of this study was to determine the effects of diesel oil vapor inhalation on serum creatine, alkaline phosphatase, SGOT and SGPT levels as indices of liver function in male rats. Methods: Thirty two rats were randomly divided into 4 groups: control and three treatment groups that exposed to diesel oil vapor for 1 hour/day, for 2 hours/day and for 3 hours/day. After a period of 6 weeks, blood samples were collected and investigated. Serum level of alkaline phosphatase, creatine, glutamate oxaloacetate transaminase (SGOT) and glutamate pyruvate transaminase (SGPT) were measured by spectrophotometry method. Results: Our findings indicated that there was no significant difference between serum alkaline level of control and experimental rats. Serum creatine level was significantly increased in rats exposed to diesel oil for 1hour/day, 2h/day and 3h/day (P<0.001, P<0.01 and P<0.001, respectively). Also, SGOT was significantly decreased in rats exposed to diesel oil for 2h/day and 3h/day (P<0.01 and P<0.05, respectively). SGPT was non-significantly decreased in rats exposed to diesel oil vapor compared with control animals. Conclusions: We have shown that exposure to diesel oil vapor can bring about enhanced kinase level, decreased SGPT level indicating the health risk caused by exposure to diesel oil inhalation, in particular, to liver.