Geyik, Mehmet Faruk/0000-0002-0906-0902WOS: 000281404900018Fever of unknown origin is defined as a temperature higher than 38.3 degrees C lasting three weeks or longer and not beind diagnosed even after one week of study in-hospital settings. Infections and malignancies had been the most common causes of fever of unknown origin overall. Nasopharyngeal carcinoma,constituting less than 0.03% of all malignant tumors and only 2% of all head and neck cancer. Ebstein Barr virus infection consumption of smoked and salted fish and vitamin-C deficient diet have been blamed in its etiology. In this study,we present two cases who were admitted to our clinic with fever of unknown origin initially and later diagnosed with nasopharyngeal carcinoma atypically progressing