Geranium oil is one of the most frequently used oils in aromatherapy. However, there is a large and diverse variation in the composition of commercial geranium oil, which depends only partly on its country of origin. The bioactivity of 16 commercial samples of geranium oils was assessed in vitro against 25 different bacteria, 20Listeria monocytogenesstrains and 3 filamentous fungi; the antioxidant and pharmacological effect was also studied and the results correlated against the chemical composition. The results show that the wide variability in bioactivity between samples cannot be directly correlated with the country of origin nor the main chemical components. This suggests that the many different paramedical effects of geranium oil, which are accredited to geranium oil regardless of its chemical composition, may be due to its action as an odor through the limbic system.