Mesenchymal hamartoma of the liver is a rare benign tumor, usually presenting in early childhood. Five children with mesenchymal hamartoma of the liver pathologically verified at Seoul National University Children's Hospital between 1978 and 2000 were analyzed retrospectively. There were two girls and three boys, and their mean age at the operation was 16.0months (range, 4 - 32 months). Three patients presented with abdominal distension. A patient was detected incidentally, and another was detected by prenatal ultrasongraphic examination. Tumor size ranged from 10x8.5cm to 34x29cm. Three tumors were located in the right lobe and two in the left lobe. Four cases underwent complete surgical resection, and the other one underwent incomplete surgical resection and marsupialization. Recurrence or malignant transformation was not noted. Five patients survived without evidence of disease for 35, 36, 38, 142 and 228 months. In conclusion, although mesenchymal hamartoma of the liver is benign lesion, it may be confused, and mixed with embryonal sarcoma. A recent report showed recurrence or malignant transformation after partial excision of the tumor. Therefore, complete excision of the tumor with surrounding normal liver tissue is recommended.