We describe a patient who was admitted with uncontrolled thyrotoxicosis and carbimazole induced neutropenia. She required 80 mg of carbimazole daily. The patient declined radio-iodine treatment because she had a little child and wished to have thyroid surgery. She received four doses of filgrastim (Granulocyte-colony stimulating factor) which maintained the neutrophil count within a reasonable level while she continued to receive carbimazole to prepare her for surgery. After a curative subtotal thyroidectomy and discontinuation of the carbimazole, the patient’s white cell count remained normal. Subsequently the patient was euthyroid on levothyroxine replacement. Carbimazole should always be discontinued if neutropenia occurs but this case demonstrates that in exceptional circumstances filgrastim can be an effective therapy while continuing carbimazole in the short term.