Objective To discuss the appearances of focal nodular hyperplasia(FNH) of the liver on the muhiphase helical CT scanning, and to improve its diagnostic accuracy with CT. Methods Helical CT scanning of pre- and post- contrast arterial phase,portal venous phase and delayed phase was performed in 10 cases with surgically and pathologically proved FNH. Results On pre- contrast scans,9 of 11 FNH lesions were hypodense(either homo-geneous or non-homogeneous), the other two lesions were isodense. On the arterial phase scans, all lesions were markedly and homogeneously enhanced,except for the central scar area. Tortuous and dilated arteries were seen at the center or peripheral area in 3 out of 11 lesions. On the portal phase and delayed phase scans ,4 of 11 lesions turned to isedanse of slightly hypodense,7 lesions remained slightly hyperdense. Central scar was found in 8 FNH lesions ,2 of them showed no enhancement while the other six demonstrated late enhancement. Conclusion Mulfiphase helical CT scanning can fully reflect the blood supplying and pathologic features of FNH, and it is of great value in diagnosing and differentiating FNH.