Fibroblasts, particularly myofibroblasts, affect the malignant progression of cancer cells in vitro. However, to date few reports have addressed the clinical significance of myofibroblasts in the gastric cancer microenvironment. This study examined the correlation between myofibroblast expression and clinicopathological features in gastric carcinoma. A total of 265 primary gastric tumors resected by gastrectomy were stained with antibodies against α-smooth muscle actin and vimentin. Stromal cells positive for vimentin were considered to be fibroblasts. Myofibroblasts were defined as fibroblasts positive for α-smooth muscle staining. Myofibroblast-positive gastric carcinoma was established when myofibroblasts accounted for more than 25% of fibroblasts in the cancer stroma. Myofibroblast expression was positive in 92 (35%) of the 265 gastric carcinomas. Myofibroblast expression showed a significantly (p<0.001) high frequency in advanced gastric cancers (76 of 146), in comparison to the early stage cancers (16 of 119). Taken together, there was a statistically significant correlation between myofibroblast expression and scirrhous type gastric cancer (p<0.001), lymph node metastasis (p<0.001), lymphatic invasion (p<0.001) and peritoneal dissemination (p=0.005). The prognosis of patients with tumors positive for myofibroblast expression was significantly (p<0.001) worse, while a multivariate analysis revealed that myofibroblast expression was not an independent prognostic factor. These findings suggest that myofibroblasts are associated with scirrhous gastric cancer. Overexpression of myofibroblasts may therefore be a useful prognostic indicator of gastric carcinoma.