The paper is based on field research conducted in 2007-2010 at the Zawady Experimental Farm which owned by Siedlce University of Natural Sciences and Humanities. The purpose of the research was to determine the effect of manuring with undersown catch crops on yields and cultivation profitability of table potato as compared to farmyard manure. The total yield of potato tubers were determined at harvest. In addition, production value, direct production cost and gross margin were calculated. The study determined that highest potato tuber yields were harvested from persian clover/westerwolds ryegrass-manured plots. Also yields of persian clover-manured potato tubers differ significantly from yield harvest from farmyard manure-treated plots. The higherst production value was obtained when table potato cultivation included manuring with persian clover or a persian clover/westerwolds ryegrass mixture.