Cell Kinetic information is an important adjunct to histologically based tumor classification. Although the rates of proliferating tumor cell have been reported to be a marker for the malignant potential of several tumors, the clinical significance of proliferative activity in laryngeal malignancy has not yet been fully investigated. Among the various approachs for evaluating the proliferative activity, proliferating cell nuclear antigen(PCNA) has been recently introduced as an antigenic marker of cellular proliferation. The authors investigated the PCNA expression rate by immunohistochemical staining for monoclonal antibody to PCNA in 26 squamous cell carcinoma of the larynx. The results were as follows : 1) The average of PCNA expression rate was 37.67±11.10% in squamous cell carcinoma of the larynx. 2) The PCNA expression rates were 29.95±8.52%, 41.77±5.12%, and 53.0±4.38% in Grade I, Grade II and Grade III, respectively. The histopathologic differences were statistically significant(p<0.001). 3) The PCNA expression rate was 35.00±11.31% in the cases without recurrence and 44.30±7.42% in the cases with recurrence of the primary lesion, that was statistically significant(p<0.05). 4) The PCNA expression rate was higher in cases with metastasis than in cases without metastasis, although the difference was not statistically significant. We concluded that the result of PCNA expression rate was correlated with the histopathologic grade and was a useful indicator to predict the prognosis in laryngeal malignancy.