Microwave-assisted extraction (MAE) of vaccarin from the seeds of Vaccaria segetalis was optimized in this study. Compared with the conventional extraction methods, maceration extraction (ME), ultrasonic-assisted extraction (UAE) and heat reflux extraction (HRE), MAE possessed higher efficiency for the extraction of vaccarin. The MAE conditions including methanol concentration, temperature, liquid/solid ratio, and microwave power were studied and optimized. The maximum extraction rate of vaccarin reached 0.52%, under the optimal conditions: methanol concentration 57%, temperature 65 degrees C, liquid/solid ratio 50 mL/g, and microwave power 400 W. At these optimal extraction parameters, the maximum extraction rate of vaccarin obtained experimentally was found to be very close to its predicted value. Furthermore, MAE extract of vaccarin exhibited substantial free radical-scavenging activity with an IC50 value of 0.48 mg/mL, which indicated crude extracts possess good potential in food and pharmaceutical industry. (C) 2014 Elsevier B.V. All rights reserved.