Knowledge on foods nutritional composition, in particular vegetables and fruits, plays a significant role in human diet, given that they are important sources of bioactive and antioxidant compounds. Currently, their consumption has increased due to physiological benefits and/or diseases risk reduction. The goal of the present study is to evaluate the chemical-nutritional composition, bioactive components and antioxidant activity of the seed (MS), seedless fruit (MF/S) and whole fruit (MF) of Rosa rubiginosa (Rosa eglanteria L.) from San Luis, Argentina, and their eventual application as functional foods. In MS, the content of proteins, fatty matter and crude fiber is higher than in the other parts analyzed (4.35 ± 0.05, 7.69 ± 0.55 and 11.66 ± 0.28 g/100 g, respectively); and MF/S presents the highest ash content, 7.11 ± 0.06%. It is noted the high linoleic acid content (43.10-37.61%), followed by α-linolenic (32.63-28.64%) and oleic (15.41-16.92%) acid in MS and MF, respectively. The values of total phenols obtained for MF and MF/S (119.11 ± 1.58 and 116.21 ± 2.12 mg/100 g dw of gallic acid) are significantly higher than for MS. Regarding the antioxidant activity measured by DPPH, the inhibition percentage does not present significant differences among the three studied samples 93.37, 93.76 and 93.47%, which are values considered as with high radical scavenging activity. The obtained results are a contribution to the knowledge on the nutritional properties and antioxidant activity of R. rubiginosa fruit and seed, which would allow diversifying their consumption and be considered as an emerging nutritional food.