We immunolocalized p16 and Rb1 in 82 surgically resected esophageal high-grade squamous cell carcinomas (46 poorly differentiated and 36 basaloid squamous cell carcinomas) and 15 esophageal small-cell carcinomas in order to clarify the clinical and biological significance of p16. The gene discussed is CDKN2A; the disease is basaloid squamous cell carcinoma.