Plant-derived phenolic compounds such as those found in red wine, tea, and certain fruit juices may protect against cardiovascular disease by detoxifying (scavenging) superoxide and other unstable reactive oxygen species. We present a laboratory exercise that can be used to assess the superoxide-scavenging capacity of beverages. Among the beverages examined, only those known to be rich in phenolic compounds (red wine, green tea, blueberry juice, and stout beer) exhibited appreciable superoxide scavenging. White wine and a 10% ethanol solution served as controls and did not scavenge superoxide. (Contains 3 figures.)