This study was conducted to determine the proximate compositions, nutritional components, and antioxidant effects of white and brown enoki mushrooms (Flammulina velutipes). The crude protein and carbohydrate contents were higher in the brown than white mushrooms, whereas the moisture, crude ash, crude lipid, and dietary fiber levels were lower. The mineral contents of the white mushroom was higher than levels obtained in the brown mushroom for the detected components (Ca, Cu, K, Mn, Na, and P). The amount of vitamin B3 in the brown mushroom was 1.51 mg/100 g, which was 4.5 times higher than that in the white mushroom. The major fatty acids detected were palmitic acid, linoleic acid, and α-linolenic acid. The total polyphenol and flavonoid contents were highest in 70% ethanol extracts of the white and brown mushrooms, respectively. For the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, a 70% methanol extract of the white enoki mushrooms showed an activity of 76.4% (p<0.05). For the ferric-reducing antioxidant power (FRAP) activity, a 70% methanol extract of the brown enoki mushrooms showed the highest value. Further, the total flavonoid contents were significantly correlated with the DPPH and FRAP activities.