The study included 2 groups of broilers COB 500, 40 birds each: one control group and one experimental group treated with pro/prebiotic Biomin C-EX. The purpose of the study was finding of some possibilities for improving the productive performances and prevention of gastroenteropathies in chickens, by administration in drinking water of the pro/prebiotic Biomin C-EX. At the 21 days and end of our studies we have collected blood samples. It has been demonstrated that the studied product no side effects, induced an increase of biochemical parameters. Has positive effects on the activity of the liver, are well tolerated by broilers and influence positively the proantioxidant system. The viability of broilers constituted 97.5% and 95% in the experimental and control groups, respectively.