The accuracy of liver scanning was evaluated in 124 cases with primary or metastatic liver tumors, including a few benign localized lesions and in 277 cases without such lesions. All findings were histologically verified by operation or autopsy. 1) Of the 124 cases with space occupying lesions(SOLs) in the liver, 92 cases were detected by liver scan(sensitivity 74.2%). And of the 277 cases without such lesions, 266 cases were evaluated as no SOLs(specificity 96.0%). The overall accuracy was 89.3%. 2) The authors evaluated the liver scan sensitivity in each of different diseases with SOLs. The sensitivity was 88.9% in primary liver carcinoma, 82.4% in primary liver carcinoma with cirrhosis, 88.7% in liver abscess, and 100% in hemangioma. The sensitivity was low in metastatic tumor(65.8%). 3) The sensitivity of the SOLs in the right lobe was 53.3% and left lobe 27.7%. In the interlobar area, detectability was 41.7%. 4) The authors compared the sensitivity of the liver scan with the size of the SOLs. The smaller the size of the SOLs, the lower the detectability. In the pachy lesions, the sensitivity was 46.6%.