The common geranium (Geranium macrorrhizum L.) is the economically most important species of the genus Geranium, and is highly valued for its fragrance and medicinal properties. Object of the present study is the essential oil (EO) prepared by hydro-distillation of aerial parts and rhizomes of common geranium from four floristic regions of the country. Its quality was determined by GC-MS analysis. The antioxidant potential of G. macrorrhizum was evaluated by the DPPH method. Forty-two compounds were identified. In the EOs from the aerial parts, the compound in the most quantity was the sesquiterpene germacrone (from 51.41 to 62.58 %). In the EOs from the rhizomes, this compound was only 5.80-8.94%. The most common ingredient of the rhizome EO was another sesquiterpene: cis-β-elemenone in a quantity from 45.20 to 50.64%. Other nine compounds were present only in the rhizome samples, among which the sesquiterpene globulol was found in good quantities: 15.71 – 15.90%. Monoterpenes like α-terpinene and phellandrene, and sesquiterpenes like eudesm-11-en-4α,6α-diol and eudesm-7(11)-en-4-ol acetate were detected only in some EOs from the aerial parts. The radical scavenging potentials of the EOs were from 33.15 to 41.79 µmol TE/100 µg EO, the rhizome samples showing weaker antioxidant potential compared to the aerial parts. Pearson correlation coefficients between the main ingredients of the EOs from the aerial parts and the radical scavenging potential pointed to the strongest impact of germacrene A on thе antioxidant value. The large differences in the results are due to the different agro-ecological conditions under which the plants were grown.