Abstract: QU Cai-jie*, SHI Tong-xin, BI Jian-ping, LI Yong-xi, WEI Hong-jun, LI Chun-xia. *Department of Dermatology, Qingdao Municipal Hospital, Qingdao 266011, China Corresponding author: LI Chun-xia, Email: txtbikao@126.com 【Abstract】 Objective To detect the expression of Livin, an apoptosis-inhibiting protein, and Smac, an apoptosis-promoting protein, in basal cell carcinoma（BCC） lesions. Methods Skin specimens were obtained from the lesions of 80 patients with BCC and normal skin of 30 human controls. Immunohistochemical SP method was used to detect the protein expression of Livin and Smac in these specimens. Chi-square test was conducted to compare the expression rate of Livin and Smac protein between the lesional and control specimens. The relationship between the protein expression of Livin and Smac in BCC was analyzed by Spearman correlation coefficients. Results The expression rate of Livin protein was significantly higher （77.50% vs. 3.33%, χ2 = 49.04, P ＜ 0.001）, while that of Smac protein was statistically lower （46.25% vs. 100%, χ2 = 26.47, P ＜ 0.001） , in BCC than in the control specimens. No significant difference was observed in the expression rate of Livin or Smac protein between nodular ulcerative and pigmented BCC specimens（75.41% vs. 80.00%, χ2 = 0.001, P ＞ 0.05; 47.54% vs. 40.00%, χ2 = 0.28, P ＞ 0.05） or between nodulocystic and pigmented BCC specimens （73.58% vs. 80.00%, χ2 = 0.03, P ＞ 0.05; 45.28% vs. 40.00%, χ2 = 0.13, P ＞ 0.05）. There was a negative relationship between the protein expression of Livin and Smac in BCC lesions（r = －0.432, P ＜ 0．01）. Conclusion The upregulated expression of Livin and downregulated expression of Smac may be invoved in the occurrence and development of BCC. 【Key words】 Neoplasms, basal cell; Inhibitor of apoptosis proteins; Apoptosis regulatory proteins