This study was carried out to determine the usefulness of imprint cytology for detecting p53 protein in breast carcinoma. NCL-DO7 (Novocastra, U.K.) was used to detect p53 protein immunocytochemically. A total of 33 cases was studied, Immunostaining of imprint cytology with NCL-DO7 was positive in 64% (21/33) and showed relatively high coincident rate (80%) with immunostaining of formalin-fixed, paraffin-embedded specimen p53 protein was related to negative estrogen receptor status, but not to the nuclear grade, lymph node metastasis, or tumor size. The fact that p53 protein expression was not related to nuclear grade might be due to predominance of nuclear grade 3. It was easier to determine the nuclear grade is one of the most important prognostic factors, in imprint cytology than in tissue specimen. p53 protein tended to be stained more strongly in imprint cytology than in tissue. It is concluded that the application of imprint cytology in p53 protein detection can be performed easily, and that it may contribute to the evaluation of prognostic factors in breast carcinoma.