The histologic type of nasopharyngeal carcinoma can be an important factor in the prognosis. The effects, if any, of the degree of cellular pleomorphism is uncertain.In this report, we present a case of nonkeratinizing, undifferentiated nasopharyngeal carcinoma with monstrous tumor giant cells. An extremely high level of aneuploidy and dense cytoplasmic accumulation of Epstein-Barr virus capsid antigen were found in tumor cells. The patient was treated with concomitant chemoradiotherapy.Nine years of follow-up with no recurrences suggests that this extreme morphologic variation may impart no adverse prognostic effect.