The unclear DNA content was measured with flow cytometry (FCM) in 167 specimens of normal nasopharyngeal epithelium (NE), adjacent tissue to carcinoma (ATC) and nasopharyngeal carcinoma (NPC). All 20 patients with NE showed diploid, whereas 38 (38%) of 101 patients with NPC, 7 (58%) of 12 patients with recurrent NPC, 6 (30%) of 20 patients with ATC and 2 (33%) of 6 patients with NE, positive to EBVCA-IgA test, showed nondiploid. In addition, cellular proliferation index (PI) of diploid NPC and diploid ATC, though differed nonsignificantly, was significantly increased as compared with that of NE (P < 0.01). The rate of cervical metastasis in nondiploid NPC was significantly higher than that in diploid NPC (P < 0.025).