Mesenchymal hamartoma of the liver (MHL) is a benign and rare hepatic lesion, with an uncertain etiology and a potential for developing into an undifferentiated distant embryonal sarcoma after an incomplete resection. It mainly presents as progressive abdominal distension with normal blood works. Most cases are diagnosed in the first two years of life, with a higher frequency in boys and on the right liver. We report the case of a mesenchymal hamartoma of the left liver in an 18-month-old girl, with a rough evolution and a literature review. There were performed an abdominal computed tomography (CT) scan and resection of the lesion. The macroscopic and histological examination described a 16.5×17.9×10.5 cm multicystic mass as a MHL lesion. MHLs may have a malignant potential and in the clinical presence of a "neoplastic" syndrome there requires a good diagnosis and drastic surgical treatment.