OBJECTIVE--To analyse the prognostic factors in papillary thyroid carcinoma, and in particular to evaluate the accuracy of the pathological tumour, nodes, metastases (p-TNM) staging. DESIGN--Retrospective univariate and multivariate analysis. SETTING--University hospital in Norway. SUBJECTS--167 patients who were operated on for papillary thyroid carcinoma between 1971 and 1985. Main outcome measures--Death of papillary thyroid carcinoma, and length of recurrence free survival. RESULTS--Male sex, increasing age, larger tumours, and spread of growth beyond the thyroid all independently increased the risk of dying of papillary thyroid carcinoma, whereas the period of recurrence free survival was influenced only by the presence of regional metastases and the patient's age. The age related p-TNM staging is suitable for predicting the likelihood of death, but is less accurate in the prediction of recurrence free survival. The age of 45 years is too low to be useful in predicting survival, especially in women. CONCLUSION--The identification of sex in the multivariate analysis as a strong independent predictor of death of papillary thyroid cancer suggests that the prognostic value of the age related p-TNM staging system could be improved if sex was adjusted for, and if a different age was used for men and women.