Primary thyroid lymphoma is an uncommon disorder of the thyroid gland. It is an aggressive yet potentially curable malignancy when diagnosed early and treated appropriately. We present three cases who presented with rapidly enlarging neck swelling of approximately one month duration and stridor. Contrast enhanced computed tomography of neck showed enlarged thyroid gland compressing trachea and displacing major vessels. All three patients underwent isthmusectomy and tracheostomy under general anaesthesia. Histopathology showed features of diffuse large B cell lymphoma. They were planned to receive chemo-radiation. Two became seriously ill and one was lost to follow-up. Therefore, early consideration should be given to the possibility of primary thyroid lymphoma in patients presenting with rapidly enlarging neck swelling and stridor. Contrast enhanced computed tomography provides quick useful information to plan for surgical management of airway and immunohistochemistry of tissue provides key information in making the diagnosis. Prognosis is grave when the patient presents late.