Immunohistochemical analysis of p53 has become an established method of detecting mutated p53. Immunolocalization of p53 has been extensively studied in tissue sections of many human neoplasms, but not in cytology specimens. Therefore, we performed immunolocalization of p53 in both cytology and tissue preparations obtained from the same specimens in 19 cases of human esophageal squamous-cell carcinoma. Three different antibodies, PAb1801, DO-7, and CM-1, were employed. Positive p53 nuclear immunoreactivity was observed in carcinoma cells, but not in noncarcinomatous cells, in both tissue and cytology preparations. The incidence of p53 positivity was 53% (10/19) in cytology and 42% (8/19) in tissue, and the coincident rate of both results was 89% (17/19). We conclude that immunohistochemistry of p53 in cytology is a useful method for detecting p53 mutations, and may contribute to the diagnosis of malignancy, because it is a simple, easy, and rapid technique.