We present the management of a case of fetal goitrous hypothyroidism (FGH) referred to our centre on completion of the 31th week with a view to prenatal treatment. The fetus displayed an anterior neck mass recognizable as thyroid by location and texture. The mother had normal thyroid function tests and no antithyroid antibodies. A cordocentesis was performed to reveal hypothyroid status, also checking the fetal karyotype which was a normal male. Intraamniotic injections of L-thyroxine 500 μg were carried out weekly. After six applications of the dose the pregnancy reached 38+5 weeks when normal delivery ensued, the newborn presenting a euthyroid status. He grew up to a healthy boy, now seven years of age, with completely normal motor and intellectual development. The rationale behind diagnosis, prenatal treatment and appropriateness of such management is discussed in this article.Keywords: Congenital Hypothyroidism, Fetal Goiter, Fetal Therapy, Prenatal Diagnosis, Cordocentesis, Amniocentesis.