The aim of this research work is to establish the capabilities of an electronic nose device to distinguish between different mixtures of herbs that are employed in a popular South American beverage (“mate”). Through the variability of the emitted odors it is possible to classify different brands and also it can constitute a useful tool for qualitty assurance procedures to guarantee homogeneity of production. We have employed a prototype of an electronic nose (Libra Nose) based on eight piezoelectric sensors provided by Technobiochip. Samples from three different brands were analyzed. They correspond to three mixtures of leaves sold under different commercial trademarks. Each standardized sample was put inside a 50 liter glass box so that diffusion of the odors is done under stationary conditions. The inlet to the nose pump was located 10 cm above the sample. Air was injected to the nose at a 0.2 liter/minute rate. Each sample was measured for time periods up to two hours and sensors response values were registered every two seconds. We have also analyzed the long term “odor” from the three mixtures.