In this study the prognostic importance of p53, proliferating cell nuclear antigen (PCNA), and Ki-67 expression was analyzed along with the clinical parameters in 35 consecutive patients with undifferentiated nasopharyngeal carcinomas. Immunohistochemistry was used to detect p53, PCNA, and Ki-67 staining. Among the clinical findings, stage IV disease (P = 0.01), cranial nerve paralysis (P = 0.02), and lymph node metastasis (P = 0.06) were associated with shorter survival. The p53 positivity correlated with the presence of lymph nodes, but it was not a significant factor to predict the outcome. PCNA expression was not found to be a prognostic indicator, On the other hand, the proliferative value of Ki-67 staining was suggestive of prognosis. A proliferation index of Ki-67 less than 10% indicated longer survival (P = 0.03). There was no correlation between Ki-67 staining and PCNA index. As a result, the prognostic value of Ki-67 may alert the physician to more aggressive and adjuvant treatment modalities.