The paper will demonstrate the quality of some feed used in swine diet. The emphasis will be on feed whose incorporation into mixes could result in unfavorable effects on production, health and economic production of swine. Data will be presented on maize and its possible negative effects, having in mind toxins. Soybean meal, or genetically modified soybean meal, will also be observed. The next feed which will be discussed will be soybean whey obtained by different procedures and the potential dangers of its use in swine diet rations. Sunflower meal, feed of animal origin, with emphasis on fish flour and meat-bone flour will also be covered in the work. A feed which has been attracting particular attention lately is yeast imported from Italy. Its quality characteristics will be discussed, the so-called non-protein nitrogen. Analyses of mineral feed will include sources of phosphorus, phosphates (monocalciumphosphate, dicalcium phosphate) phytases and resolving the problem of phosphorus in swine rations. Finally, an inevitable segment are synthetic amino acids, especially lysine and its role in swine diet.