RTOG proposed a multivariate modelling system predicting the response of head and neck cancers to radiation therapy in 1984. The aim of this study was to veri(y whether PPC (Probaility of primary clearance calculated by a multivariate modelling system) had any correlation with the survival in the patients with carcinoma of the nasopharynx following radiation therapy Analysing 81 patients with carcinoma of the nasopharynx treated with radiotherapy between January 1, 1971 and December 31, 1983 at Yonsei University College of Medicine, Yonsei Cancer Center the actuarial 5 year survival rate was $36\%$ and median survival was 39 months. The survivals for Group 1 (27 who had more than $80\%$ of PPC), Group 2 (20 who had between 71 and $80\%$ of PPC), and Group 3 (29 who had less than $71\%$ of PPC) were $66\%$ (median survival months : more than 72), $27\%$ (31), and $4\%$ (12) respectively. There was a definite correlation between PPC and survival among the three groups.