Natural zeolites contain micro-and macroelements such as calcium, magnesium, potassium, iron and copper. The aim of the following study has been to determine changes in poultry production induced by adding naturally occurring zeolites as dietary supplements. The study was carried out on 20,000 one-day chicks of the fattening breed called Ross. The birds were divided into two groups: the control group (group C) and the group supplemented with 5% of zeolite added to the feed (group E). Observations lasted for 45 days. Weekly measurements of the body weight of randomly chosen chicks were taken in both groups, and dead birds were counted. The composition of faeces was analyzed with an absorbance test. The air composition was determined with an instrument specially designed for that purpose. Differences in the body weight between groups C and E reached approximately 10%. A decrease in the mortality rate among chicks was observed in the treatment versus the control group. Mineral substances such as calcium and phosphorus were higher by about 4.4% and 9.5%, respectively, in the experimental group. Less ash in faeces (by about 20.4%) and less ammonia in the air (by about 33%) were determined for the experimental group, too. The present results may have important implications for poultry production, especially the fact that zeolite supplementation increased the body weight gain and reduced the number of falls. In conclusion, it is recommended to include zeolite in feed additives. © 2014, Polish Society Magnesium Research. All rights reserved.