Abstract: Objective To investigate the relationship between expressions of c-IAP1 and bax proteins and cell apoptosis of thyroid carcinomas. Methods Immunohistochemical method(SP) was used to detect expression of c-IAP1 and bax proteins in thyroid neoplasm. The apoptosis were detected by TUNEL. Results Among 20 cases of thyroid adenomas(TA),the positive expression rates of c-IAP1 and bax proteins were 25.0% and 60.0% respectively, AI was 0.33±0.21；Among 47 cases of thyroid carcinomas (TC), the positive expression rates of c-IAP1 and bax proteins were 87.2% and 89.3% respectively, AI was 0.91±0.37. The expressions of c-IAP1 and bax proteins and AI in TA were significantly different from those in TC（P＜0.05）. AI of c-IAP1 positive group was lower than that of negative group in TC，AI of bax positive group was higher than that of negative group in TC. Conclusion The results indicated that c-IAP1 and bax proteins might play an important role in development of thyroid carcinomas；High expression of c-IAP1 protein might reduce inhibit the cell apoptosis of thyroid carcinomas, high expression of bax protein might promote the cell apoptosis of thyroid carcinomas.