Abstract: Objective To determine the diagnostic value of Ornithine carbamoyltransferase in hepatic diseases.Methods In optimal alkaline phosphate buffer, Citrulline was used as substrate and added to a sort of enzymatic reactions.Serum OCTactivity of healthy adult and hepatopathy was determined by the rate of speed method with automatic biochemistry analyzer.Results The activity of OCT was significantly higher in acute viral hepatitis and hepatic encephalopathy patients.There was a statistically significant correlation between OCT and serum ALT, AST, and GGT.In chronic hepatitis, liver cirrhosis and hepatoma, the value of OCT was medium to high with at least 90% positivity rate.OCT activity of alcoholic hepatitis and drug induced hepatitis patients is slightly high.Conclusion OCT is a sensitive and specific index to reflect hepatic injury.It can be detected by the rate of speed method which is accurate, easy and provide results simply.It can also be applied as a routine monitoring index for early acute viral hepatitis and late chronic liver disease.