Background: Exposure to chronic low levels of aflatoxin B1 (AFB1) contamination can lead to immune suppression and nutritional consequences that might greatly contributed in the increase of hepatocellular carcinoma (HCC). The toxicity of AFB1 is greatly vary between different population, affected by age, gender, and environmental factors. Material and subjects: Aflatoxin B1 (AFB1) was measured in 50 blood samples collected from non B, C hepatitis viruses and non CMV-Ab liver disease patients from different general hospitals and polyclinic in KSA during period 01-2013 to 06-2014. All Patients demonstrate elevation of ALT and AST with unknown etiology. Serum samples were obtained and kept at −20 °C for AFB1detection. Results: Out of the 50 blood samples, 38 demonstrate a detectable serum level of AFB1 while the remaining 12 patients were AFB1 negative and used as control participants. While AST was non-significantly different in AFB1 exposed patients, ALT was significantly higher in AFB1 positive samples compared to control AFB1-negative. AFB1 was positively correlated with AST and ALT as liver function enzymes and with age as a risk factor of long duration of AFB1 chronic exposure. Multiple linear regression analysis ascertained the association between AFB1 chronic exposure and ALT increase in liver dysfunction Saudi patients. Conclusion: Measurement of elevated ALT as marker of liver injury in AFB1 chronically exposed Saudi patients can help to avoid the future development of HCC. Moreover, early detection of AFB1 exposure, together with early vaccination against HBV and HCV can remove the synergistic effects of these two etiological factors and thus decrease the risk of developing liver cancer.