Benalaxyl-M [methyl N-phenylacetyl-N-2, 6-xylyl-DL-alaninate] is a newly introduced phenyl-amide fungicide whereas Mancozeb is one of the member of ethylenebisdiothiocarbamate (EBDC) fungicide. Benalaxyl-M in combination with Mancozeb effectively controls downy mildew of grapes. A two season field trial was conducted under West Bengal climatic condition during 2009-2010 to evaluate the dissipation pattern of fungicide mixture (Benalaxyl-M 4 % + Mancozeb 65 %) WP in grapes at two application rates (2,750 g and 5,500 g ha(-1)). The quantitative analysis was performed using liquid chromatography-mass spectrometry (LC-MS/MS) and UV-Vis spectrophotometer for Benalaxyl-M and Mancozeb residues respectively. Following the first order kinetics the fungicide Benalaxyl-M dissipates in grapes with half-life (T(1/2)) value ranges between 2.59 and 2.79 days irrespective of seasons and doses. The dissipation pattern of Mancozeb also follows first order kinetics with half-life (T(1/2)) value ranges between 3.86 and 4.93 days irrespective of seasons and doses.