The purpose of this study was to assess the significance of the expression of p21WAF1/Cip1 and proliferating cell nuclear antigen (PCNA) in human laryngeal squamous cell carcinomas. Forty-eight patients (25 supraglottic, 23 glottic) who had undergone operations between 1998 and 2003 were included in this study. The Envision immunohistochemistry method was utilized to stain these tissue specimens. The results showed that the immunostaining of p21WAF1/Cip1 do not show any correlation with differentiation, N stage, metastasis, survival, recurrence or the laryngeal site of involvement. A significant inverse correlation was detected between p21WAF1/Cip1 and the T stage. In contrast, the percentage of PCNA labelled cells showed a significant correlation with the T stage, but not with other clinicopathological parameters. There were differences in the expression of p21WAF1/Cip1 and PCNA between the supraglottic and the glottic carcinomas. In conclusion, our findings suggest that p21WAF1/Cip1 and PCNA may play an important role in the progression of carcinoma of the supraglottic larynx.