Opuntia species have been used for centuries as food resources and in traditional folk medicine for their nutritional properties and their benefit in chronic diseases, particularly diabetes, obesity, cardiovascular diseases, and cancer. The aim of this study was to evaluate the antioxidant activities and anti-inflammatory effects of 75% ethanol extracts from Opuntia ficus-indica fruits (OFFE) and Opuntia humifusa fruits (OHFE). The total polyphenol and total flavonoid  contents of OFFE were 17.07±0.08 and 8.65±0.08 mgQE/g, respectively, whereas those of OHFE were 9.41±0.14 and 2.03±0.08 mgQE/g, respectively. The antioxidant activities of OFFE and OHFE were determined based on various radical scavenging activities using 1,1-diphenyl-2-dipicrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. The DPPH and ABTS radical scavenging activities of OFFE were significantly higher than those of OHFE. In addition, the release of nitric oxide (NO) and reactive oxygen species (ROS) were ameliorated by pretreatment with OFFE and OHFE in a dose-dependent manner. OFFE also suppressed the secretion of pro-inflammatory cytokines, including interleukin-1β (IL-1β) and interleukin-6(IL-6) but not tumor necrosis factor-α (TNF-α) from lipopolysaccharide (LPS)-stimulated RAW 264.7 cells, but the OHFE did not decrease cytokine expression. These results suggest that OFFE exhibits strong antioxidant activity and anti-inflammatory effects and can be developed as a potential therapeutic candidate for diseases involving oxidative stress and inflammation.