A review of liver sonograms obtained for cancer patients (excluding primary liver cancers) over a 12 year period found 829 benign lesions: non-parasitic cysts (427 cases), hemangiomas (216 cases), solitary calcifications (79 cases), focal fatty infiltration (62 cases), and miscellaneous lesions (45 cases). These benign pathologies represented 41.8% of the focal hepatic lesions observed during this period in this population; hepatic metastases accounted for the remaining 58.2%. Marked female predilection was noted for the nonparasitic cysts, hemangiomas, and focal fatty infiltration; 63–78.7% of these lesions were solitary, and first-line imaging by US was sufficient for diagnosis of 66.1–98.2% of cases. Analysis of lesion evolution over more than 5 years revealed modifications in 17% of hemangiomas, 23.9% of nonparasitic cysts, and 75% of cases of focal fatty infiltration. Systematic pretherapy liver sonography can be proposed owing to the high frequency of benign liver lesions that can create diagnostic problems during follow-up of cancer patients.