Garlic (Allium sativum) has an important dietary and medicinal role for centuries. It is a large annual plant of the Liliaceae family, which grows in most of Africa and in Ethiopia. Ethiopian garlic is used in traditional medicine for infectious disease and some other cases. The present study tested the aqueous extract of garlic in vitro for its antibacterial activity. The extract showed concentration dependent antibacterial activity against Staphylococcus aureus. The traditional use of Ethiopian garlic for infectious diseases and for controlling fever appears to be justified.