Nasopharyngeal cancer is one of poor prognostic head and neck cancer, because of its complex anatomical structure and early metastasis. After the role of E-B virus in nasopharyngeal cancer had been established, many studies have been reported dealing with E-B virus and its relation to nasopharyngeal cancer, but rare in Korea. The purpose of this paper were to quantitate antibody titers against E-B virus and to determine prospectively whether a relationships exists between antibody titers and clinical course and histopathologic type of tumor by clinical study and Enzyme linked Immunosorbent Assay of 41 patients, diagnosis as nasopharyngeal cancer in Yonsei Medical Center from January 1985 to March 1986. The result as follows : 1) Male to female ratio was 2.4 : 1, and the mean age was 57.4 in male, and 44.9 in female. 2) The site and frequency of first symptom were as follows. Nasal symptom was 35.7%, neck mass 33.4%, ear symptom 14.0%. 3) The distribution of clinical stage were as follows : Stage 4 was 46.5%, stage 3 36.5%, stage 2 9.7%, stage 1 7.3%. 4) Histopathological distribution of nasopharygeal cancer were as follows : undifferentiated epidermoid cancer was 39.0%, non-keratinizing epidermoid cancer 34.2%, keratinizing epidermoid cancer 26.8%. 5) The geometric mean of antibody titers of sera from healthy doner against E-B virus was 89, the positive rates were 85.4%. 6) Antibody titers of sera from patients with untreated nasopharyngeal cancer differed from titers abtained from other comparison group statifically significantly. Other head and neck cancer patients were higher than healty controls in titers. 7) In relationship between clinical stage of nasopharyngeal cancer and antibody titers, the number of patients in some group was still small, so the firm conclusion cannot be abtained but, there was a trend toward high positive rate with high stage. 8) The antibody titers of sera from patients of WHO type 2 were greater than WHO type 1 significantly. No difference was seen between WHO type 2 and WHO type 3. 9) Antibody titers of sera from nasopharyngeal cancer with untreated were higher than treated patients significantly.