A differentiation between hepatocellular carcinoma (HCC) and benign liver lesions is required. The aim of the study was to perform an analysis of the time of enhancement of focal liver lesions in a contrast-enhanced ultrasound (CEUS) examination. The curves of enhancement and the homogeneity of the tumor enhancement were assessed. The study included 52 patients with diagnoses of hepatocellular adenoma (18), focal nodular hyperplasia (11) and HCC (28). The study included magnetic resonance imaging or computed tomography and a comparison of the obtained information with CEUS. In the benign lesions groups after 20–30 s, the enhancement was similar to the liver parenchyma. In the HCC group, the enhancement was slightly less intense compared to the liver parenchyma and the benign lesions. The difference of the enhancement in the arterial phase (benign lesions vs. HCC) wasp= 0.0452, and the difference of enhancement in the late venous phase (benign lesions vs. HCC) wasp= 0.000003. The homogeneity of the enhancement (benign lesions vs. HCC), respectively, wasp= 0.001 in the arterial phase,p= 0.0003 in the portal venous phase andp= 0.00000007 in the late venous phase. Liver tumors can be classified as benign when they are homogenous in the arterial phase and don’t present washout. HCC in the arterial phase is inhomogeneous and washout is observed in the venous phases. When radiological symptoms suggest malignant lesion, CEUS can be used to select the best biopsy access.