Phyllanthus urinaria, a widely used herb medicine in Asia, was tested for its anti-tumor effect in vivo for the first time. The anti-tumor activity in P. urinaria extract was evaluated by its effect on tumor developed in C57BL/6J mice with implantation of Lewis lung carcinoma cells. The oral administration of P. urinaria to mice caused significant inhibition of tumor development with lower occurrence rate and markedly reduced tumor size. Neither the total body weight of mouse nor the weights of organs including heart, lung, liver, spleen and kidney revealed any difference between two groups, suggesting limited in vivo cytotoxic effect of P. urinaria in mice. TUNEL assay demonstrated the increase of apoptosis in tumor sections prepared from P. urinaria-treated mice compared with control mice. It is worth of note that the neovascularization in tumor was inhibited in P. urinaria-treated mice, which implicated the potential anti-angiogenic effect of P. urinaria. Further study using an in vitro matrix-induced tube formation of HUVECs again confirmed the anti-angiogenic action of P. urinaria. P. urinaria exerted no inhibitory effect on the growth of HUVECs, however, the migration of HUVECs as analyzed using transwell assay was suppressed markedly by P. urinaria in a dose-dependent manner. All together, the present study indicated that P. urinaria extract is an anti-tumor and anti-angiogenic agent, which can be used safely in animals.