ObjectiveTo evaluate the expression and prognostic significance of ALDH1A1 in gastric neuroendocrine carcinoma. Materials and methodsImmunohistochemical stains of ALDH1A1 were evaluated in 67 cases of gastric neuroendocrine carcinoma. The findings were correlated with clinicopathologic variables and overall survival. ResultsImmunohistochemistry revealed positive cytoplasmic immunoreactivity in 35 of 67 (52.2%) tumors and strongly positive immunoreactivity in 14 of 67 (20.9%). Strongly positive ALDH1A1 expression, but not positive staining, was significantly associated with lymph node status, lymphovascular invasion, and ki-67 index (P=0.039, 0.045, and 0.045, respectively). Kaplan‐Meier survival curves and log-rank tests showed significantly poorer prognoses in cases of high ALDH1A1 expression compared to cases of low ALDH1A1 expression or the negative control group (MST, 17 vs. 52 months; P=0.026). Multivariate analysis showed that high ALDH1A1 expression, lymph node metastasis, and lymphovascular invasion had significant associations with decreased overall survival (P=0.029, 0.008, and 0.005, respectively). ConclusionsHigh ALDH1A1 expression may be a prognostic indicator of survival in patients with gastric neuroendocrine carcinoma.