The performance of a cutting fluid obtained from an onion extract was evaluated in terms of the tool wear after drilling operations of an AISI 304 austenitic stainless steel using HSS tools. These results were compared with that of two commercial cutting fluids. Measurements of the flank and tip wear were carried out every forty holes by comparison of the images of the used tool and its initial state. A relationship between wear patterns in drills and the nature of the cutting fluids has been proposed. The experimental results suggest that the onion extract has a good performance and protects the flank and the tip of the drill in a more homogeneous way, while the commercial fluids protect only the tip or the flank of the drill. Considering the difficulty for machining austenitic stainless steel and that the onion extract used in this work does not have any kind of additives, this extract shows a high potential for being used as a base in a cutting fluid in future developments.