We evaluated the clinical significance of p53, p27 and PCNA expressions in esophageal squamous cell carcinomas. Operative specimens obtained from 70 patients with esophageal squamous cell carcinomas were investigated by staining with antibodies against p53, p27 and PCNA. The correlations among p53, p27 and PCNA expression, clinicopathologic factors and prognosis were studied. The expression of p53 was observed in 55.7%, and it did not correlate to histologic classification, growth pattern, and lymphatic invasion. The expression of p27 was observed in 48.6%, and it correlated to lymph node metastasis. The PCNA positive index (PCNA-PI) was high in the p27 negative cases. The p53 positive and p27 negative group revealed the worst survival rate among groups. Therefore, the p27 positive case, often associated with well differentiated carcinoma, tends to have a slower tumor-growth rate and better prognosis. It is suggested that immunohistochemical assessment on the p53 and p27 expressions would be useful to the recognize the malignant potential and differentiation of squamous cell carcinoma of the esophagus.