Ultra-weak luminescence of serum in 30 normal persons and 40 patients (12 laryngeal cancers, 18 laryngopharyngeal cancers, and 10 benign tumour patients) was studied using SHG-1 type photobiological photometer. The results showed that the intensity in malignant tumour group was higher than that of the benign group, which in turn was higher than that of the normal group with significant statistical differences (P < 0.05). The study implied that ultra-weak luminescence test is of value in diagnosis of laryngeal and laryngopharyngeal cancers.