To determine whether p53 gene transcripts were altered in thyroid tumor and adjacent tissues of thyroid tumor, total RNA from 12 tumor specimens (9 carcinomas and 3 adenomas) and 4 adjacent tissues of thyroid tumor was exmined by Northern blot hybridization and reverse transcription——polymerase chain reaction. It was found that p53 gene transcripts were present in all tumors and the adjacent tissues of tumor and were significantly more obvious in the samples of carcinomas as compared with those of adenomas and in the samples of tumor as compared with those of the adjacent tissues of tumor. These data suggest that excessive p53 gene expressions are involved in thyroid carcinogenesis.