High performance liquid chromatographic (HPLC) analysis of mycelia of Sclerotium rolfsii grown in broth medium supplemented with garlic (Allium sativum) and onion (Allium cepa) was carried out to estimate qualitative and quantitative changes in phenolic acids. Several phenolic acids, such as gallic, chlorogenic; ferulic, o-coumaric and cinnamic acids were detected in varied amounts in mycelia grown on such media as compared to control. Phenolic acids represents a wide range of secondary metabolite found in the cells of plants and microbes including fungi. The growth characters of S. rolfsii in various supplements also varied from thin and transparent to thick and opaque.