Purpose : To evaluate the relative value of arterial, portal venous and delayed phase images of spiral CT in he detection of metastatic tumor of the liver. Materials and Methods: Forty-three metastatic tumors in twelve patients were underwent tri-phasic spiral CT examination with injection of 120 ml ionic contrast material (36 g of iodine) at the rate of 3 ml/sec. Arterial, portal venous and delayed phase CT images were obtained 35, 65, and 360seconds after the start of contrast injection, respectively. Results : Arterial phase images detected 35(81%),portal venous phase images 43(100%), and delayed phase images 34(79%) lesions, respectively(p<0.05). All masses larger than 2cm(n=23) were detected in all three phases, whereas 60%, 100%, 55% of the masses smaller than2cm(n=20) were detected in arterial, portal venous and delayed phase CT, respectively. The best contrast between masses and the hepatic parenchyma was in portal venous phase followed by arterial and delayed phase(p<0.01). In two hypervascular masses, the contrast was better in arterial phase. Conclusion : Portal venous phase of spiral CT is optimal in the detection of metastatic tumor of the liver. Arterial phase may be helpful for the detection of hypervascular metastasis. Delayed phase should be used restrictively.