Abstract: Objective To investigate the occurrence，development and special biological behavior of skin basal cell carcinoma(BCC). Methods The expressions of connexin43，Kai1 and PTEN proteins were detected by immunohistochemical S-P method in 35 patients with BCC，10 case with normal tissues and 18 patients with squamous cell carcinoma(SCC)；And the expressions of Cx43 mRNA were detected by in situ hybridization.The expression levels (positive area and optical density)of connexin43，Kai1 and PTEN proteins and Cx43 mRNA were detected respectively by computerized image-analysis in normal skin, BCC and SCC.All the data were input into the computer and statistically analyzed with SPSS(13.0) software. Results (1) Cx43 protein and mRNA showed strongly positive expression in skin epidermis tissues，positive or weakly positive expression in BCC group，and negative or weak positive in SCC group. Compared with normal skin group and SCC group，the expressions（positive area and optical density）of Cx43 protein and mRNA in BCC group were significant increased（P<0.01）；(2) Kai1 and PTEN protein showed strongly positive expression in skin epidermis tissues，positive or weakly positive expression in BCC group，and negative or weak positive in SCC group. Compared with normal skin group and SCC group，the expression differences of Kai1，PTEN protein in BCC group all had significantincreased（P<0.05）；(3) There was a positive correlation between the expressions of PTEN and Kai1 (r=0.629，P<0.01)， PTEN and Cx43 (r=0.519，P<0.01)，as well as Cx43 protein and its mRNA(r=0.732，P<0.01) in BCC. Conclusion s(1) The lower expression of Cx43, Kai1，PTEN proteins and Cx43 mRNA might be play important roles in BCC occurrence and development. (2)The higher expression of Cx43，Kai1，PTEN proteins and Cx43 mRNA in BCC was related to the biological characteristics such as slow growth and rare metastasis.