This aim of this study was to determine the effect of the application of a prebiotic preparation containing mannanoligosaccharides, in diets for broiler chickens on health status and meat quality. In the diets for broiler chickens an acidifier and a herbal preparation (control group) were replaced with a prebiotic preparation Biolex MB 40 (mannanoligosaccharides) at 2 kg/t of the diet (group II). In group III, Biolex MB 40 was applied at 2 kg/t and an acidifier. At 21 days of age, blood samples from birds were drawn. The following were determined in the serum: total protein level, γ-globulins, lysozyme and ceruloplasmin. After slaughter chemical analysis of breast muscles was carried out. The application of a prebiotic preparation Biolex MB 40 at 2 kg/t positively affects the production results, expressed as body weight, feed utilization and the European Efficiency Index. The mechanisms of non-specific defence against infections were observed to activate in the chickens fed on the diets with the examined preparation, which was expressed as an increase in lysozyme level in blood serum. The meat of the examined chickens contained similar amounts of dry matter, crude ash, crude protein and crude fat.