Quantification of tumor vascularization has recently been shown to be a parameter of potential prognostic significance in various types of malignant tumors. To determine the prognostic value of tumor vascularization in esophageal cancer, tumor samples from 150 patients with squamous cell carcinoma of the esophagus and 10 samples of normal esophageal mucosa were stained immunohistochemically with the monoclonal antibody QBEND/10 (CD34), which recognises endothelial cells. Using light microscopy, the number of microvessels was counted in the areas with the highest microvessel density (MVD). The microvessel density was significantly higher in the normal esophageal mucosa (mean: 130/mm2) than in the tumor samples (mean: 69/mm2, p = 0.0001). Correlation of the MVD in the tumor tissue with other prognostic factors showed significantly lower microvessel counts in tumors with lymphatic-vessel invasion (p = 0.0076) and in high pT-stages (p = 0.0081). No significant correlation was found between the MVD and pN stage, tumor size, tumor grade, blood-vessel invasion and proliferative activity. In the univariate survival analysis no significant differences were found between poorly vascularized tumors and highly vascularized tumors. A Cox proportional hazard regression selected the parameters lymphatic-vessel invasion (p = 0.0001), pT stage (p = 0.0034) and pN stage (p = 0.0256) but not MVD as independent prognostic variables.