Serological and biochemical studies were done at the National Taiwan University Hospital, on 243 patients with biopsy-proved anaplastic nasopharyngeal carcinoma (NPC) in various clinical conditions. The remarkable elevation of both IgG and IgA antibody titers against EB virus was specific for NPC patients. The seropositive rates ranged from 75% to 100% in various stages of NPC patients. Serum IgG and IgA levels were also increased moderately and nonspecifically in stages II-IV and recurrent patients. Peripheral white blood cell count was also slightly increased in these patients. Peripheral lymphocyte counts were slightly decreased in patients with neck recurrence or distant metastasis. Serum IgM, C3, C4 and Acid phosphatase levels were within normal range in all the patients. Serum GOT, GPT, alkaline phosphatase, and lactate dehydrogenase were elevated in some of patients with distant metastasis and in most of those with liver metastasis. Mucoprotein was elevated in about 10% of stage II-IV patients but in about 50% of patients with recurrent neck metastasis or distant metastasis. in conclusion, serological and biochemical examinations are important in the diagnosis of late stages and recurrence or metastasis of NPC.