PURPOSE: P53 and cyclin D1 have been evaluated as a prognostic marker in papillary thyroid carcinoma (PTC). However, the relationship between p53/cyclin D1 and PTC prognosis has not yet been confirmed. Therefore, we investigated the relationship between p53/cyclin D1 and PTC prognostic factors. METHODS: 919 patients with PTC were enrolled. Immunohistochemistry slides were reviewed for p53 and cyclin D1 immunoreactivity. Patients were classified into two groups according to the p53 and cyclin D1 grade: negative for < or =5% and positive for >5%. Medical records were reviewed to evaluate the prognostic factors, lymph node metastatic ratio (LNMR), and MACIS score. We analyzed patients based on p53/cyclin D1(-/-), p53/cyclin D1(-/+), p53/cyclin D1(+/-), p53/cyclin D1(+/+) separately for evaluation of independent effect of p53 and cyclin D1. RESULTS: Mean age of the patients was 49.73 years (range 15~87), and tumor size was 1.19 cm (range 0.1~5.0). P53 was positive in 809 (88.0%) and cyclin D1 was positive in 748 (81.4%). Positivity of p53 and cyclin D1 were correlated (r=0.448). There was no statistical significance in MACIS score. Positivity of p53 and cyclin D1 were related with larger tumor size, older age, early T stage, more tumor capsulation, and female. LNMR was higher in p53/cyclin D1(+/-) than p53/cyclin D1(-/-) (P=0.036), p53/cyclin D1(-/+) than p53/cyclin D1(-/-) (P=0.034), and p53/cyclin D1(+/+) than p53/cyclin D1(-/-) (P=0.007). CONCLUSION: There was no consistent relationship between p53/cyclin D1 and worse prognostic factors of PTC. However, LNMR was higher in p53(+) and cyclin D1(+) cases independently, much more in p53/cyclin D1(+/+) than p53/cyclin D1(-/-).