Manganese in animal organisms is responsible for proper bone formation and many biochemical processes. The aim of the study was to determine the effect of manganese oxide nanoparticles (NanoMn2O3) as a mineral additive to the feed mixture on the growth, slaughter characteristics, femur bone strength, mineral content of tissues and Mn excretion. The male chickens were randomly divided between a control group without Mn2O3 in a premix, three groups receiving NanoMn2O3 (nano group 30, 60 and 100 % of the standard level) and three groups receiving Mn2O3 (30, 60 and 100 % of the standard level). Each group consisted of seven birds. The highest feed intake and body weight at 42 day was in the 60 % nano group, but there were no differences in the feed conversion rate. Slaughter characteristics, physicochemical properties, bone morphometry, the content of Mn in tissues and health status evaluated by blood parameters were not affected by supplying different forms of Mn2O3. Furthermore, the excretion of Mn was lower in NanoMn2O3 than in Mn2O3 groups. The results indicate that the application of NanoMn2O3 had no negative effects on chicken growth and development, but reduces Mn excretion, suggesting that commercial Mn2O3 can be replaced by NanoMn2O3 in broiler diets. However, follow-up research at farm conditions is necessary to validate the results.