The energy expenditure and energy cost of activities of grazing beef cows were determined (by using the heart-rate method and GPS collars with motion sensors) on different size plots on Mediterranean foothill herbaceous rangeland, in three seasons. In winter plot size had no effect on the time spent on each activity or on the energy cost of these activities. In the summer, however, when the herbage was dry, cows on large plots grazed longer and expended more energy on grazing activity. It is suggested that on larger plots cows could select herbage of better quality than when grazing smaller plots.