Although garlic (Allium sativum) has been extensively studied for its health benefits, sprouted garlic has received little attention. We hypothesized that sprouting garlic would stimulate the production of various phytochemicals that improve health. Ethanolic extracts from garlic sprouted for different periods had variable antioxidant activities when assessed with in vitro assays, including the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity assay and the oxygen radical absorbance capacity assay. Extracts from garlic sprouted for 5 days had the highest antioxidant activity, whereas extracts from raw garlic had relatively low antioxidant activity. Furthermore, sprouting changed the metabolite profile of garlic: the metabolite profile of garlic sprouted for 5-6 days was distinct from the metabolite profile of garlic sprouted for 0-4 days, which is consistent with the finding that garlic sprouted for 5 days had the highest antioxidant activity. Therefore, sprouting may be a useful way to improve the antioxidant potential of garlic.