We investigated effect of small black soybean fraction (SBSF) T cell-mediated responses for tumor surveillance and proliferation in leukemia cells in vitro. Each SBSF butanol fraction (SBSFBu) and SBSF chloroform fraction (SBSFCh) was administered p.o. once a day far 21 days in BALB/c mice and then levels of serum cytokines and subpopulation of lymphocytes were measured. Moreover, SBSF fraction was treated into the cultured various cell lines for proliferation in leukemia cell lines, NO production by RAW264.7 cells, and expression of p53 gene in U937 leukemia cells. These results showed that SBSFBu increased levels of serum IL-4but not IL-2 and IFN-${gamma}$, and increased expression of CD4$^+$ T cells and CD8$^+$ T cells in splenocytes in vivo, while SBSFCh increased levels of serum IL-2 and IFN-${gamma}$ but decreased IL-4, and increased CD8$^+$ T cells but not CD4$^+$ T cells. Moreover, both of SBSFBu and SBSFCh inhibited proliferation of HL60, U937, and L1210 leukemia cell lines in a dose-dependent manner, up-regulated NO production by RAW264.7 cells in a dose-dependent manner, and enhanced expression of p53 gene in U937 leukemia cells. Our findings indicate that SBSFBu and SBSFCh may enhance T cell-dependent immune responses, and that both of SBSFBu and SBSFCh may inhibit proliferation of leukemia cells by up-regulation of NO production and expression of p53 gene.