Typically, Kaposi's sarcoma (KS) also presents with immune cell infiltrates. This study does immunophenotype characterization for demographics of some of these cells to test the hypothesis that ‘development of end-stage (nodular/tumor) KS is associated with numeric alteration in immune cell infiltrates.’ Fifteen cases of classic-KS (nodular/tumor) and 20 normal biopsies were examined using antigen-antibody reactions and immunoperoxidase staining for histiocytes (CD68), B cells (CD20) and T cells (CD3). Variations between normal and lesions were observed with significant increases in immune cell infiltrates (2.3 ± 0.6 vs. 6.4 ± 0.4); CD68+ (4.0 ± 1.0 vs. 7.0 ± 0.5); CD3+ (3.0 ± 1.1 vs. 10.1 ± 0.8); and CD20+ (0.0 ± 0.0 vs. 0.3 ± 0.0). Increased density of immune cells in the nodular lesions of KS may reflect increased antigenicity of these lesions; the increase in T cells suggests enhanced T cell activity in KS. However, these issues should be tested by further studies.