Clinical thyrotoxicosis is rare in molar pregnancy and has yet to be reported in a patient with a partial mole. Human chorionic gonadotropin (hCG), which has thyrotropic activity, is believed to be responsible for hyperthyroidism of gestational trophoblastic activity and hyperemesis gravidarum. We report the first case of hyperthyroidism presenting as thyroid storm in a partial molar pregnancy. Normal thyroid function returned after the partial mole was evacuated, and the biochemical improvement correlated with declining hCG levels. This case highlights the importance of including partial mole in the differential of hCG-mediated hyperthyroidism.