The effect of using a warm breastshield on the efficiency, effectiveness, and comfort of expressing milk with an electric breast pump was assessed. The authors tested a standard breastshield at 25°C and a breastshield warmed to 39°C on 25 mothers using their maximum comfortable vacuum or -125 mm Hg. Using a warm breastshield effectively warmed the nipple and areola and, combined with maximum comfortable vacuum, decreased the time to remove 80% of the total milk yield and increased the percentage of available milk removed after 5 minutes of expression, with no change in the percentage of available milk removed after 15 minutes of expression compared with an ambient-temperature breastshield. The data confirmed that use of the mother's maximum comfortable vacuum was more efficient than a vacuum of -125 mm Hg. Using a warm breastshield with an electric breast pump was comfortable and improved the efficiency of milk removal.