β-Zearalenol is a nonsteroidal estrogen of the resorcylic acid lactone group related to mycoestrogens found in Fusarium spp. β-Zearalenol is the β epimer of α-zearalenol and along with α-zearalenol is a major metabolite of zearalenone formed mainly in the liver but also to a lesser extent in the intestines during the first-pass metabolism. β-Zearalenol is about the same or slightly less potent as an estrogen relative to zearalenone. Contamination of grains by Fusarium species, notably maize, gives rise to high levels of zearalenol and is regarded as an important food quality issue for both human and animal health.