Background: This study aimed to examine the clinical significance of fatty acid synthase (FASN) expression ingastric cancer (GC), and investigate any prognostic role. Materials and Methods: FASN expression was assessedin gastric cancers by immunohistochemistry using 60 paraffin-embedded tissue specimens, and clinical datawere collected by retrospective chart review. Moreover, FASN mRNA expression in 15 fresh resected specimenswas evaluated by the reverse transcription-polymerase chain reaction (RT-PCR). Immunohistochemical stainingof PTEN was performed to assess the correlation of PTEN with FASN in gastric cancer. Results: Increasedexpression of FASN was noted in gastric cancers. The frequency of FASN gene amplification was also significantlyhigher in gastric cancer than in adjacent normal tissue. FASN expression in human gastric cancer tissues wassignificantly correlated with patient TNM stage and peritoneal dissemination (p<0.05). Moreover, higher FASNexpression significantly correlated with shorter overall survival (p<0.05). Here, upregulation of FASN negativelycorrelated with PTEN expression in gastric cancer. Conclusions: These findings indicate that FASN expression isupregulated in gastric cancer, and increased FASN may be critical to th peritoneal metastasis and survival. Ourresults suggest that FASN upregulation and PTEN downregualtion may be involved in peritoneal disseminationfor gastric cancer progression.