Objective To further clarify the pathogenesis of different types of Kaposi′s sarcoma (KS) by measuring the protein expressions of caspase-3 and E-cad in tumor tissues of Xinjiang Uygur patients with acqured immunodeficiency syndrome (AIDS)-Kaposi′s sarcoma (KS) and classical KS. Methods From July 2011 to October 2014, 38 patients with KS at the First Affiliated Hospital of Xinjiang Medical University and Urumqi Infectious Disease Hospital were enrolled, among whom 28 were male and 10 were female, and all of them were uygur. Immunohistochemical and Western blot methods were used to detect the expressions of caspase-3 and E-cad proteins in 22 cases of AIDS-KS patients and 16 cases of classic KS. The quantitative data of normal distribution were analyzed by t test, while count data were compared with χ2 test with R × C table. Results KS lesions in patients with classic KS were confined to the skin, without mucosal, lymph node or visceral involvement. Lesions in AIDS-KS patients were not only confined to the skin and superficial lymph nodes, but also oral mucosa involved in 12 cases and internal organs involved in 7 cases. Liver and lung involvement was more common. The CD4+ T lymphocyte count in patients with AIDS-KS was (200.8±166)/μL. All 15 AIDS cases with CD4+ T cell count less than 200/μL developed opportunistic infections.CD4+ T lymphocyte count of patients with classic KS was (562.52±222.66)/μL and the 16 patients with CD4+ T lymphocyte count greater than 350/μL had no opportunistic infections.The results of immunohistochemistry showed that the positive expression rate of caspase-3 protein in KS tissues in patients with AIDS-KS was 68.2%, in patients with classic KS was 100.0%, with significant difference between two groups (χ2=7.37, P=0.01). The positive expression rate of E-cad protein in KS tissues in patients with AIDS-KS was 72.7%, in patients with classic KS was 100.0%, with significant difference between two groups (χ2=5.18, P=0.03). Western blotting showed that the gray value of caspase-3 in the KS tissue of patients with AIDS-KS was 0.55±0.36, and that in patients with classic KS was 0.86±0.56, with significant difference between two groups (t=-2.070, P<0.05). The gray value of E-cad in the KS tissue of patients with AIDS-KS was 0.54±0.41, and that in patients with classic KS was 0.85±0.45, with significant difference between two groups (t=-2.060, P<0.05). Conclusions There are differences in the protein expressions of caspase-3 and E-cad in tumor tissues of patients with AIDS-KS and classical KS in Xinjiang Uygur patients with Kaposi's sarcoma, which may correlate with a faster progression and a higher mortality rate for AIDS-KS. Key words: Acquired immunodeficiency syndrome; Sarcoma, Kaposi; Caspase 3; E-cad