A new system for the notation of intra-oral carcinomata has been described. It differs from all previous TNM classifications in that both the site (S) and the pathology (P) have been taken into consideration in addition to the conventional tumour (T), node (N) and metastasis (M) generally used. Both of these additional features have been recognized as important factors in assessing the prognosis of the patient. This new system additionally functions as a means of disseminating the maximum of clinical information succinctly and in a readily communicable format. A further innovation has been the introduction of a means of quantitatively assessing the significance of particular clinical and pathological features and from these values predicting the prognosis. For comparative purposes we have defined four stages corresponding with the stages used in the conventional TNM classification. We have applied the STNMP classification to a random sample of 136 cases of intra-oral carcinomata with more than 5 years follow-up. Particularly in defining those patients with a good prognosis, i.e. 5 year plus survival, this system has proved to be considerably more accurate than the existing staging methods. We propose that for a trial period this system should be widely used in parallel with the conventional TNM classification and staging in order to evaluate its true worth in the clinical situation. With further use it will probably be necessary to adjust the numerical weighting given to particular features, but this can only be accurately assessed when a very large number of patients has been evaluated. Our figures support the clinical impression that patients with poorly differentiated squamous cell carcinomata have a shorter survival than those with well differentiated lesions and that the degree of differentiation of the tumour is directly proportional to the survival of the patient. When considering the site of the tumour we have based our grading on the known survival curves for squamous cell carcinomata at different sites.