The effects of frequent milking on milk quality were studied in a unilateral, short-term milking experiment. In period one, 11 cows were milked on each udder half twice daily; in period two one udder half was milked twice daily while the contralateral was milked four times daily. In the more frequently milked udder half the milk yield, FFA content and average fat globule size increased. No effect was observed on fat content, fatty acid composition and γ-glutamyl transpeptidase. The plasmin activity decreased but no proteolytic degradation of milk proteins was observed. Concentration of Na decreased while K increased.