OBJECTIVE: To evaluate the expressions of Ki-67, p53 and p21 waf1/cip1 according to the age and the histologic type of preinvasive and invasive cervical lesions. MATERIAL AND METHOD: Microwave-oven-processed formalin-fixed, paraffin-embedded, cervical biopsy specimens and hysterectomy specimens were obtained from 1997 to 1998 at the Soonchunhyang university Chunan hospital. These included 55 cervical intraepithelial neoplasm(CIN I-III), 14 invasive squamous cell carcinoma and 3 adenocarcinoma, and immunohistochemically evaluated by monoclonal MIB-1 antibody, monoclonal p53 antibody, and monoclonal p21 antibody. Positive index was expressed as a percentage of strong staining cells per 300 counted cells in evenly strong staining area. RESULT: Ki-67, p53 and p21 protein were expressed in the nuclei. Ki-67 was specifically expressed in all phases of cell cycles in proliferating cells. p21 expression was not seen in CIN I and CIN II, but was increased with increasing histologic grade. According to the age, Ki-67 expression was significantly higher in 30 > or =aged group than 30 < or = aged group, but p53 expresson was not significantly different according to age groups, and p21 expression was significantly lower in 50 < or = aged group than 30 > or =aged group. CONCLUSION: Conclusions of this study indicate that cell proliferating rate is higher in young age groups than old age groups. p53 expression was not significantly different according to age and histologic grade. These indicates that mutation of the p53 gene may be associated with the development of cervical cancer, but not associated with the progression of cervical cancer. Besides, p21 expression was increased in increasing histologic grade, but decreased in old aged women. Further study of this paradoxical increase in p21 expression in cervical carcinoma is necessary to clarify the mechanisms of p53 indepent pathway.