Objective To detect the expression of selenium binding protein 1 ( SBP1 ) in gastric cancer cell line SGC7901, BGC823, normal gastric epithelial cell line GES-1, gastric cancer tissues and normal gastric tissues, explore the relationship between SBP1 and pathologic features, and discuss the feasibility of SBP1 as an diagnostic marker of gastric cancer. Methods The clinical data of 135 patients with gastric cancer who were admitted to Zhongnan Hospital of Wuhan University from 2006 to 2007 were retrospectively analyzed. The expression of SBP1 in the gastric cancer tissues and 16 cases of normal gastric tissues were detected by immunohistochemistry. The mRNA and protein expressions of SBP1 of SGC7901, BGC823 and GES-1 were determined by Western blot and RT-PCR. All data were analyzed by using chi-square test and one-way analysis of variance.Results The mRNA expressions of SBP1 in BGC823 and SGC7091 were 0. 120 ± 0. 020 and 0. 133 ± 0. 015,respectively, which were significantly lower than 0. 907 ± 0. 015 in GES-1 ( F = 2106. 462, P < 0.05 ). The protein expression of SBP1 in BGC823 and SGC7901 were 0.253 ±0.015 and 0.273 ±0.015 ,respectively, which were significantly lower than 0.877 ±0.025 in GES-1 ( F = 1026. 758, P <0.05 ). A strong positive reaction of SBP1 was observed in 3 cases of gastric cancer tissues and 16 cases of normal gastric tissues. The decrease of the protein expression of SBP1 was correlated with clinical stages of the patients ( x2 = 12. 629, P < 0.05 ), rather than the sexes, ages, tumor histological types, tumor differentiation, infiltration depths and lymph node metastasis (x2 =2. 142, 0.860, 1.838, 5.001,4.858, 1.994, P>0. 05). Conclusions The decrease of SBP1 expression could be used as a marker in diagnosing gastric cancer. Down-regulation of SBP1 expression may play an important role in the genesis and prognosis of gastric cancer. Key words: Gastric neoplasms; Selenium binding protein 1; Immunohistochemistry