Musashi 2 (MSI2), a marker of stem and progenitor cells, has been identified as an oncogene. Various investigations have revealed that MSI2 is differently expressed in several types of blood cancer and solid cancers. However, its expression and biological functions in gastric cancer (GC) remain unclear. In the present study, MSI2 mRNA and protein expression were assessed in GC tissue samples. The associations between MSI2 mRNA expression and the clinicopathological characteristics of patients with GC were analyzed, and the effect of MSI2 on the prognosis of patients with GC was verified. The biological functions of MSI2 in GC cells were assessed using gain-of-function assays in vitro. The results revealed that MSI2 was overexpressed in the majority of GC tissue samples, although this difference was not significant. MSI2 mRNA expression levels were associated with invasion depth, tumor-node-metastasis stage, degree of differentiation and tumor size (P<0.05), but were not associated with sex, age, tumor location or human epidermal growth factor receptor 2 expression. Increased MSI2 expression resulted in a poorer prognosis in patients with GC (χ2=4.221; P=0.040). In vitro assays revealed that MSI2 promoted MKN-28 cell proliferation, migration and invasion, and promoted tube formation in HUVECs. Although no significance of MSI2 expression was found, its oncogenic functions in the GC cell line indicated that MSI2 may be a potential oncogene that may serve as a biomarker for GC diagnosis and prognosis with verification from a larger sample and more GC cell lines.