Arginine deiminase (ADI) and L-arginine (L-Arg) can act as anti-tumor agents in-vitro and in-vivo. However, the mechanism of ADI and L-Arg as anti-tumor agents has not been clearly shown.With the goal of understanding the role of ADI and L-Arg in inhibition of cell growth, we used the Ramos human lymphoma cell line, which is known to be ADI-sensitive, and observed the p53 and NF-κBp65 protein expression after ADI and arginine treatment. After determining an optimal experimental ADI concentration (0.01 U/ml), we studied the effects of ADI treatment, when combined with different concentrations of L-arginine (control, ADI only, ADI with 10 mM/ml Arg, ADI with 30 mM/ml Arg, and ADI with 50 mM/ml Arg). An MTT assay was used to assess cell survival after treatment, Western blot analysis to determine the levels of the NF-κBp65, p53 and NO mediators and nitric oxide assays were used to determine nitrite levels.L-arginine enhanced ADI-induced inhibited cell growth through expression of NF-κBp65 and p53 in a dose-dependent manner.