Several authors have reported the usefullness of radiological investigation of nasopharyngeal soft tissue in the lateral skull roentgenogram in detecting abnormalities. But often otolaryngologist are faced with a dilemma in diciding in whether nasopharyngeal soft tissue in normal or over abundant. Thus the author under took a radiological examination of nasopharyngeal soft tissue in the lateral skull roentgenograms of normal adults and nasopharyngeal tumor patients, to estimate the normal range of nasopharyngeal soft tissue and to detect the pathological widening of nasopharyngeal soft tissue valuable to the establishment of the diagnosis of nasopharyngeal tumor. 120 normal Korean adults, equal number of sex, ere examined who had skull roentgenograms for no disease in the nasopharyngeal region, and 30 nasopharyngeal ca. patient, equal number of sex were also examined. Results are : 1) The thickness of the posterior wall of normal nasopharynx in man was 19.6±2.7mm, and in female was 16.4±2.5mm, and it was significantly greater in man. (p<0.001). 2) The thickness of the roof of normal nasopharynx in man was 9.2±3.1mm, and in female was 6.7±2.6mm, and it also significantly greater in man(p<0.001). 3) The thickness of the posterior wall of male nasopharyngeal patient was 25.2±3.3mm, and in female patient was 22.3±3.3mm, and there were significant differences between normal and tumor patients(p<0.001). 4) The thickness of the roof of male nasopharyngeal patient was 11.2±3.1mm and in female was 8.2±2.7mm and there were significant differences between normal and tumor patients(p<0.001). 5) We estimated the 95% confidence range of the posterior wall thickness and the roof thickness of the nasopharynx.