Focal nodular hyperplasia of the liver is a nodular lesion of the liver and is a benign tumor second only to hepatic hemangioma in incidence. The etiology of focal nodular hyperplasia of the liver is not fully determined, and it may be related to congenital arteriovenous malformations of the liver, or to inflammation or trauma to the liver that causes a limited reduction in blood supply. The vast majority of patients with focal nodular hyperplasia of the liver do not present with clinical symptoms and are usually discovered incidentally during physical examination or surgery. Focal nodular hyperplasia of the liver is a benign lesion that develops slowly, has a good prognosis, and complications are rare, so regular observation and follow-up is recommended for this group of people. Surgical resection may be considered if the nodules are growing rapidly or if the diagnosis cannot be made definitively.