Herbicidal potential of CFCF (Cell free culture filtrate) of Sclerotium rolfsii against Parthenium hysterophorus was determined by shoot cut, seedling and detached leaf bioassays. Maximum phytotoxicity was obtained from 14 day's old fermented broth with sucrose + 0.5% Tween 20 as formulating agent. Significant reduction in chlorophyll and protein contents of host was also noticed.