Summer savory (Satureja hortensis L.) can be used for the preservation and/or extension of the shelf life of raw and processed foods owing to its antioxidant and antimicrobial activities. In this study, the effects of different concentrations of lyophilized water extract of S. hortensis (LSHWE) on the shelf life of ground beef were investigated. Ground beef was treated with various concentrations of LSHWE (i.e., 0, 100, 250 and 500 ppm) and stored at 4 ± 0.5C for 72 h. LSHWE concentrations had statistically significant effects on the microbial counts. In ground beef samples treated with LSHWE, mesophilic, psychrotrophic, Pseudomonas and Enterobacteriaceae decreased. Different LSHWE concentrations had also significant effects on pH. Lipid oxidation decreased, depending on LSHWE concentrations, and 500 ppm of LSHWE gave the lowest thiobarbituric acid reactive substance values, with 11.57 ± 4.07 µmol malonaldehyde/kg at the end of storage. LSHWE levels had also significant effects on color values (L*, a* and b*) of the ground beef.