In this study, the content composition and antioxidant activity of goji berry fruits from two species ( and ) were assessed. The total carbohydrate and phenolic contents were evaluated using attenuated total reflection Fourier-transform infrared (ATR-FT-IR) spectroscopy, while the antioxidant activity of fruits was examined with two in vitro methods, which are based on the scavenging activity of the 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and 2,2'-azino-bis(3-ethyl-benzthiazoline-sulfonic acid) (ABTS•⁺) free radicals. The fatty-acid profile was determined using gas chromatography coupled with mass spectrometry (GC-MS). The results of this study indicate that the fruits of present higher concentrations in carbohydrates and phenolics than Mill. fruits. Furthermore, the antioxidant activity based on the half maximal inhibitory concentration (IC ) measurements of DPPH• and ABTS•⁺ free-radical scavenging was higher in than Mill. Also, the GCMS analysis confirms the high levels of linoleic, palmitic, and oleic acids contained in the fruits of both species. Finally, the results of this study clearly show that the concentration of bioactive and antioxidant molecules is higher in than in fruits, which was also confirmed by ATR-FT-IR measurements.