The aim of the research was to determine the quality of meat of lambs fed with feeds containing lasalocid. It was ascertained that lasalocid added in the quantity of 50 mg per animal and day to the feed during the whole period of fattening considerably increased the protein content in the longest back muscle in lambs. The addition of 50 mg lasalocid to the feed considerably lowered the fat content in the muscle. The muscle of lambs receiving 50 mg of lasalocid had the best water binding capacity and thus was most suitable for the production purposes. Lasalocid influenced significantly and advantageously the intensity of colour of the muscle.