Relapse and exacerbation of Graves' disease during pregnancy is rare, and thionamide induced agranulocytosis is an uncommon side effect. We report a case of a pregnant woman in her 24th week of gestation that experienced a relapse of Graves' disease that was complicated by propylthiouracil induced agranulocytosis. Following the discontinuation of propylthiouracil and administration of a broad-spectrum of antibiotics, agranulocytosis subsided within 10 days. A total thyroidectomy to avoid any future relapse was planned and a short course of a beta-adrenergic blocker and Lugol solution were prescribed before the operation. At the 28th week of gestation, a total thyroidectomy was performed without complications and thyroxine replacement therapy was commenced. At the 40th week of gestation, labor was induced and a 3,370 g healthy male infant was born without clinical features of thyrotoxicosis. We report herein on the patient and the treatment options for this rare and complicated case.