In this book one bacterium and one fungal species were examined for their antimicrobial susceptibility against acetonic, methanolic, chloroformic and aqueous extracts of plant. The antimicrobial activity of plant extracts were assayed using well diffusion method. For both the samples Allium cepa L. and Allium sativum L. extracts, chloroformic extracts were exhibited very less inhibiting effect against bacteria and aqueous extracts were exhibited very less inhibiting effect against fungi. This study provides evidence for the presence of one or more soluble constituents in the plants used, that probably interferes with bacterial and fungal growth and their metabolism which would prevent and inhibit initiation and progression of many diseases.