Thyroid carcinomas demonstrate a morphological and biological spectrum from highly differentiated to undifferentiated (anaplastic) tumours, and the poorly differentiated carcinomas probably occupy an intermediate position, being characterized by a more solid structure. The present thyroid carcinoma, which occurred in a 77 year old male, showed a distinct cribriform growth pattern with marked apoptosis and high-grade features such as nuclear plemorphism, frequent mitotic figures, tumour necrosis and vascular invasion, suggesting the presence of a poorly differentiated carcinoma. Metastatic spread to the regional lymph nodes and lungs were present at the time of diagnosis, and the patient died after 15 months with progressive disease. It should be further studied whether cribriform structure may represent an independent feature of aggressive clinical behaviour.