A field test was conducted during 1994 to evaluate the effectiveness of post-emergence herbicide 45% MSMA S and 10% Sirius Wp on the control of weeds in Cynodon dactylon (L.) Pers. Lawn. Application of 45% MSMA S at rate of 2 kg/ha and 3 kg/ha were effective in controlling of lxeris chinensis and Kyllinga evifolia and showed the same good efficacy as the Sirius. However, the 45% MSMA S was less effective to Paspalum orbiculare and without control effect on Panicum repens.