The expression levels of nm23-H1 mRNA and its protein in human nasopharyngeal carcinoma (NPC) were detected to clarify the relationship between nm23-H1 and metastasis and prognosis of patients with NPC. nm23-H1 mRNA expression in fresh tissues from 78 patients with NPC was investigated by in situ hybridization and RT-PCR. Routine labeling streptavidinbiotin immuno-histochemistry with the nm23-H1 murine monoclonal antibody was employed to study the expression of nm23-H1 protein in paraffin-embedded specimens from 231 patients with NPC treated in our hospital. The clinical pathologic data and results of follow-up were collected. Comparisons between expression of nm23-H1 protein or mRNA and clinical outcome were performed using the 2 test. Multivariate prognostic analyses were performed by the Cox regression model. We found that nm23-H1-negative tumors were associated with a higher incidence of lymphnode metastasis (84.2%) than nm23-H1-positive ones (32.8%, p F 0.01). The distant metastasis and loco-regional recurrence rates in the nm23-H1-negative group were 55.8% and 31.68%, respectively but only 17.2% and 11.5%, respectively, in the nm23-H1-positive group (p F 0.01). A significant association was found between expression of nm23-H1 protein and prognosis (p F 0.01). Expression of nm23-H1 protein indicated favorable prognosis, suggesting that the absence of nm23-H1 protein expression was significantly associated with lymph-node metastasis, recurrence and distant metastasis in NPC. Expression of the nm23-H1 gene may be valuable for assessing the prognosis of NPC.