AIM: To explore the expression of Sp1 in gastric carcinoma as well as its association with other clinicopathologic features, and to evaluate the role of Sp1 as a prognostic Indicator of gastric carcinoma.METHODS: By using immunohistochemistry, we examined the Sp1 expression patterns in 65 cases of human gastric cancer, and 40 normal gastric mucosa specimens.Simultaneously, the correlation between Sp1 expression and clinical outcome or clinicopathologic features was investigated.RESULTS: The percentage of Sp1 expression was 12.5%(5/40) in normal gastric mucosa, and the Sp1 protein was mainly expressed in the nuclei of cells located in the mucous neck region. In sharp contrast, strong Sp1 expression was detected in tumor cells, whereas no or faint Sp1 staining was detected in stromal cells and normal glandular cells surrounding the tumors. The expression rate of Sp1 in gastric cancer lesions was 53.85% (35/65).The medium survival duration in patients who had a tumor with negative, weak and strong Sp1 expressions was 1 700, 1 560 and 1 026 d, respectively (P＜0.05). Sp1 protein expression was closely related to the depth of tumor infiltration (χ2 = 13.223, P＜0.01) and TNM stage (χ2= 11.009, P＜0.05), but had no relationship with the number of lymph nodes and Laurens classification (P＞0.05). Cox regression model for multivariate analysis revealed that high Sp1 expression (P＜0.05) and advanced stage (P＜0.01) were independent predictors of poor survival.CONCUSION: Normal and malignant gastric tissues have unique Sp1 expression patterns. Sp1 might serve as an independent prognostic factor, by influencing the tumor infiltration and progression.