A case of focal nodular hyperplasia of the liver in a 43-day-old baby girl with isolated hemihyperplasia and elevated serum alpha-fetoprotein is presented. The child referred to our hospital with bilateral renal masses detected by prenatal and postnatal ultrasonography. A mass lesion was detected in segment 6 of liver and was diagnosed as focal nodular hyperplasia. We present this case to emphasize the presence of focal nodular hyperplasia in a patient with isolated hemihypertrophy and elevated serum alpha-fetoprotein level.