Anaplastic carcinoma of thyroid is a rare high grade neoplasm with unfavourable prognosis, accounting for less than 5% of all thyroid malignancies. It is responsible for high mortality and morbidity rate due to aggressive nature of carcinoma. Anaplastic carcinoma of thyroid is infrequently reported in the literature. Here we present a rare case of anaplastic carcinoma of thyroid in a 77 year old female who presented with large neck swelling.