Beta-glucuronidase (beta-GD) activity in serum and upper respiratory tract (URT) secretion in patients with head and neck malignant tumors (HNMT) was studied. Subjects included 40 HNMT patients, 40 healthy volunteers and 40 patients with benign tumors of the head and neck region. The results showed that there was no statistically significant difference of serum beta-GD level among the three groups. The same was true for URT secretion between the normal control and benign tumor groups. beta-GD level in URT secretion was higher in HNMT group than in other groups (P < 0.001). Using healthy subjects' average beta-GD level plus two standard difference as positive standard, the sensitivity, reliability and specificity of the test were 85.0%, 92.5% and 100% respectively. beta-GD levels were higher in patients with advanced tumors and metastases. One year follow-ups of six patients showed that beta-GD level change in URT secretion was in accordance with clinical manifestations. These results suggest that assay of beta-GD level in URT secretion can be used as a valuable supplimental parameter in early diagnosis of HNMTs, their clinical staging, evaluation of therapeutic effectiveness and detection of recurrence and metastases. In addition, this method has the advantage of easy, prompt, result specificity, sensitivity and reliability.