Epidemiology investigations show that the following factors may be related with nasopharyngeal cancer: ① EB virus infection. ② Environment and diet: Environmental factor is also a reason to cause nasopharyngeal cancer. In Guangdong, investigations show that nickel content contained in rice and water in some area with a high incidence rate of NPC is lower than the area with a low incidence rate of NPC. In the hair of patients with nasopharyngeal cancer, content of nickel is very high. Animal experiments show that nickel can promote the incidence rate of NPC. Some reports also show that salted fish and pickled food are the factor to cause high incidence rate of nasopharyngeal cancer in southern part of China. And NPC is also related with the time to eat salted fish, period of consumption and amount and cooking methods. ③ genetic factors:  NPC usually appears in some races and family which had suffered this disease. Such as future generations of Chinese southerners who are living in other countries now and still maintain a high incidence rate of nasopharyngeal cancer, thus indicating that nasopharyngeal cancer is a genetic disease. ]]>