PURPOSE: The perisplenic extension of the left lobe of the liver can be misinterpreted as a splenic or perisplenic lesion on ultrasonography(US) and computed tomography(CT). The purpose of our study is to classify thelateral margin of the left lobe of the liver into three types and to evaluate the incidence and the relationship between each type and abnormal liver on CT scan. MATERIAL & METHODS: A total of 515 abdominal CT scans frompatients over 15 years old were retrospectively evaluated. Liver contours were divided into three types on the basis of degree of the left lateral extension of left lobe of the liver. Type A was defined as the lateral extension of the left lobe of liver to the medial portion of the stomach, type C as the perisplenic portion, andtype B as between the two types. Each type was further divided into normal and abnormal liver groups based onclinical, CT, surgical & patholigic findings and evaluated on its ratio of normal and abnormal liver, intrahepatic diseases associated with an abnormal liver and statistical significance between a normal and abnormal liver. RESULTS: The incidence of the three types of liver among the 515 patients was 360(69.9%), 121(23.5%) and 34(6.6%) patients in type A, B and C, respectively. Type C showed normal liver in six patients, which was 2.7% of allnormal livers(221/515) and abnormal liver in 28 patients, which was 9.5% of all abnormal livers(294/515). Type Ashowed normal liver in 49.7%, abnormal liver in 50.3% and there was not statistically significant difference between normal and abnormal liver(P>0.05). Type B showed normal liver in 29.8% and abnormal liver in 70.2% ; type C showed normal liver in 17.6%, abnormal liver in 82.4% and there was a statistically significant difference between normal & abnormal liver(P<0.001). The space occupying lesion(SOL) was most common(52.6%) in all theabnormal livers and hepatoma was the most common disease in the SOL(47.2%). In the abnormal type C liver, SOL(58%)and diffuse hepatopathy(32.8%) were most common and hepatoma and liver cirrhosis were the most common diseases,respectively. CONCLUSION: The perisplenic extension of the left lobe of the liver(type C) was seen in 6.6% of abdominal CT scans, and was frequently associated with abnormal liver conditions including SOL. Careful interpretation is needed to differentiate from splenic or perisplenic disease.