Objective To investigate the expression of suppressor gene Runt-related transcription factor 3 (Runx3) in gastric carcinoma and its relationship with clinicopathologic parameters. Methods RT-PCR and Western blot were used to determine the mRNA expression and protein expression of Runx3 gene in primary tumor and corresponding normal tissues respectively in 52 patients with gastric carcinoma. The relationship between Runx3 expression and clinicopathologic parameters was analyzed. Results RT-PCR and Western blot analysis in 52 patients with gastric carcinoma showed down-regulation of Runx3 mRNA and Runx3 protein in 59.6% (31/52) and 48.1% （25/52） of the primary tumors tested, and in none of the normal tissues (P＜0.05) respectively. There was a significant negative correlation between the expression level of Runx3 gene and the clinicopathologic parameters such as tumor size, differentiation, infiltrative depth, lymph node metastasis and TNM stage (P＜0.05， P＜0.01). Runx3 gene transcription was coincident with its protein expression (r=0.840, P＜0.01）. Conclusion The expression of Runx3 gene is down-regulated in gastric carcinoma, which suggests that Runx3 gene plays an important role in carcinogenesis and the progression of gastric carcinoma. It may be a new target of diagnosis and treatment of gastric carcinoma.