This study aims at evaluating the expression of P27, Ki67 and P53 in Squamous Cell Carcinoma (SCC), Actinic Keratosis (AK) and Bowen Disease (BD) specimens. In an analytic-descriptive setting, skin biopsy specimens of 45 patients were evaluated in three 15-case groups including BD, AK and SCC specimens. Fifteen normal skin biopsy specimens were obtained and used as the control group. Immunohistochemical staining was performed in all the specimens and the expression rates and patterns of Ki67, P27 and P53 were determined. The results were compared between the four groups. Ki67 was expressed in 0.8, 23.7, 12.3 and 19.3% of the cells in the normal skin, AK, BD and SCC groups, respectively. No significant difference was seen between the three pathological conditions regarding the expression rate of Ki67. P27 was positive in 23.4, 26.2, 25.9 and 4.5% of specimens in the normal skin, AK, BD and SCC groups, respectively. This rate was significantly the lowest in the SCC group. P53 expression was detected in 26.6, 41.8 and 54.6% of the assessed cells in the AK, BD and SCC groups, respectively. There was no expression of P53 in the normal skin specimens. This rate was significantly the highest again in the SCC group. Based on these results, the quantitative and qualitative (pattern of distribution) evaluation of the expressions of Ki67, P27 and P53 may be helpful in differentiating malignant and premalignant epidermal lesions, particularly in unsatisfactory or fragmented specimens.