Background: The antioxidant properties of ethanolic root extract of pepper fruit (Donnetia tripetala), and its effect on lipid peroxidation of some fresh beef tissues during frozen storage were investigated. Materials and Methods: The antioxidant parameters were assessed using standard methods, while malondialdehyde levels of different fresh beef tissue sections treated with the extract prior to freezing, were estimated in a colorimetric reaction with thiobarbituric acid. Results: The H 2 O 2 -scavenging ability of the extract was similar to that of ascorbic acid, with a maximum scavenging power of 55.61 ±4.98%, and an IC 50 value of 86µg/ml. The extract exhibited a concentration-dependent ferric ion-reducing power, although this was significantly lower relative to that of the ascorbic acid (p < 0.05). The total phenolic content was 212.5 ± 0.002 mg/g, while the nitric oxide-scavenging ability was 64.33 ± 0.2% after 150 min. The capacity of the extract to inhibit lipid peroxidation in frozen heart muscle slices was significantly higher than that of vitamin C (p < 0 .05), but comparable to vitamins C and E in frozen testes and kidney slices. Conclusion: These results suggest that the root extract of D. tripetala is rich in antioxidants which can be applied to meat preservation during refrigerated storage.