Objective To analyze the time-density curve of the small HCCs in the arterial phase and to find out its unique features.Methods All lesions were imaged with single-level serial SCT.The attenuations of the lesion,hepatic artery and hepatic parenchyma were measured.The time-density curve was built with these CT values and their corresponding times.Results The time-density curves of the lesion and liver parenchyma were divided into three kinds:the first kind had two intersects(73%).The first one was seen at the time when the curve of the lesion went up over the one of the parenchyma and the second was seen at the point the curve came down below the parenchyma's.There was no second intersecting point in the second type(19.2%) and the curve of the lesion was below that of the parenchyma in the third (7.7%). Conclusion The initial time of the enhancement of small SHCC is (21.6?6) s.The optimal time of the enhancement of SHCC is (36?8) s.