The purpose of the present study was to define the overexpression of cyclin D1 in superficial and advanced esophageal carcinomas and to investigate whether the expression of this molecule indicates a poor prognosis. This study included 41 patients with superficial esophageal carcinomas (Tis and T1) and 48 patients with advanced esophageal carcinomas (T2, T3, and T4). The expression of cyclin D1 in surgically resected specimens was evaluated immunohistochemically with a monoclonal antibody. Positive immunoreactivity was found in 31 of 89 cases (35%). Overexpression of cyclin D1 did not correlate with TNM classification or histologic type. Of the 48 patients with advanced esophageal carcinomas, 32 patients with cyclin D1-negative tumors survived longer than did 16 patients with cyclin D1-positive tumors (P = 0.0017). In contrast, we observed no survival difference between patients with cyclin D1-positive and -negative superficial esophageal carcinoma. These results suggest that cyclin D1 indicates a poor prognosis in cases of advanced esophageal carcinoma but not in cases of superficial esophageal carcinoma.