INTRODUCTION Hyperthyroidism is a rare complication of molar pregnancy. CASE REPORT We report a 39-year-old woman who presented a thyrotoxic syndrome accompanying a molar pregnancy. Serum thyroid hormones were elevated and returned to normal level after uterine evacuation of a molar pregnancy. The authors detail the role of thyroid stimulating property of human gonadotropin chorionic hormone and its structural changes during the gestational trophoblastic diseases. These changes give the latter the thyroid stimulating properties and signs of hyperthyroidism. CONCLUSION Molar pregnancy may be a cause of hyperthyroidism. The diagnosis of molar pregnancy should be a mention to thyrotoxicosique syndrome in a woman of childbearing age.