Docetaxel, one of the most effective anticancer drugs for gastric cancer, targets beta-tubulin, the major protein in mitotic spindles. Eight isotypes of beta-tubulin, with tissue and organ-specific expression, have been identified in mammalian cells. We examined class III beta-tubulin expression in gastric cancer and assessed its relationship with sensitivity to docetaxel-based chemotherapy. A total of 115 paraffin-embedded gastric tumors were analyzed by immunohistochemistry for class III beta-tubulin expression. Twenty patients with advanced gastric cancer received preoperative docetaxel-based chemotherapy. Their biopsied specimens, obtained by endoscopy before chemotherapy were examined for class III beta-tubulin expression. The relationship between expression and chemosensitivity was assessed. Forty-two (36.4%) of 115 cases were confirmed to be positive for class III beta-tubulin expression. There was no association between clinicopathological status and prognosis. Among the patients positive for class III beta-tubulin expression, only 16.7% showed no response to chemotherapy, while 64.3% responded to the chemotherapy in the negative group. Our results suggest that class III beta-tubulin is a simple and useful predictive marker for the clinical response to docetaxel-based chemotherapy in gastric cancer.