Abstract: Objective:To investigate the expression of maternally expressed gene 3 (MEG3), a long non-coding RNA gene, in gastric can-cer tissues; determine the relationship of MEG3 with the prognosis of gastric cancer; and explore the relationship between MEG3 and apoptosis- associated protein P 53as well as murine double minute 2 (MDM 2). Methods:Fifty- five consecutive patients with gastric cancer admitted to Qingdao Municipal Hospital for surgical treatment from September 2012to June 2013were included in this study. Gastric cancer and paired normal tissues were collected. The expression of MEG 3 was tested through real- time quantitative poly merase chain reaction (qRT-PCR). Western blot analysis was used to detect the expression of P53and MDM2 in gastric cancer and eval-uate their correlations with MEG3. Results:The expression of MEG3 decreased in cancer tissues ( 7. 98± 0. 19) relative to the correspond-ing normal tissues ( 9. 47± 0. 18) ( P<0. 05). P 53and MDM2 showed negative relationships in the gastric cancer and normal tissues. A posi -tive relationship was found between P 53and MEG 3 ( r=0. 591 , P<0. 05), whereas a negative relationship was found between MDM 2 and MEG 3 ( r=− 0. 346 , P<0. 05). The median survival time was significantly prolonged in patients with high MEG3 expression compared with patients with low MEG3 expression. Conclusion: MEG 3 exerts an inhibiting effect on the development of gastric cancer. MEG 3, P53, and MDM2 may have important relationships in the biological mechanisms of gastric cancer development. Detecting the expression level of MEG3 may be useful for the prognosis of gastric cancer.