The effect of fennel (Foeniculum vulgare) essential oil (EO) and fennel supercritical fluid extracts (SFE1 and SFE2) on lipid oxidation of beef burgers was investigated. The basic formulation of beef burgers was obtained by manually mixing fresh minced beef meat with the table salt (2%). From the obtained basic formulation, eight treatments were produced with the addition of the following ingredients extracted from fennel: essential oil (EO), supercritical fluid extract 1 (SFE1), SFE2, and also the standard compound, anethole (A). The ingredients were used at two levels: 0.075 and 0.150 μL/g. The basic formulation of the beef burger was marked as a control (without antioxidants). Lipid oxidative reactions in beef burgers were determined by a spectrophotometric method – the TBARS test. All ingredients reduced lipid oxidation in beef burgers. SFE1 and SFE2 had a higher (p<0.05) antioxidative potential than EO and anethole. Therefore, the results of this study displayed the significant antioxidative potential of fennel EO, and especially fennel SFEs, as novel natural antioxidants in beef burger processing.