A common feature of pathogenic fungi to cause disease in plant is the necessity to pass through the plant cell wall, an important barrier against pathogen attack. To this end, fungi possess a diverse array of secreted enzymes to depolymerize the main structural polysaccharide components of the plant cell wall, i.e. cellulose, lignin and pectin. In the present investigation, six pathogenic fungal species such as Alternaria sp. PMK1, Alternaria sp. PMK2, Alternaria macrospora MKP1, Alternaria macrospora MKP2, Alternaria macrospora MKP3 and Alternaria macrospora MKP4 were isolated from diseased leaves of Parthenium plant and found to be pathogenic to this weed. Isolated fungi were examined for the presence of cellulolytic, pectinolytic, amylolytic and ligninolytic activity. Presence of enzymatic activities of these fungal indicating the importance of the cell wall degrading enzymes in pathogenicity against Parthenium weed.