Abstract: The objective of this study was to determine magnitude of ammonia emissions from dairy cattle free-stall barns with natural ventilation. The measurements of ammonia concentration and indoor environmental conditions in barns were done throughout the 4 days in three dairy farms in summer season. The overall hourly average temperature and relative humidity for all barns were 26.5°C and 61%, respectively. In monitored dairy cattle barns, ammonia concentrations were observed between 0.4 and 8.77 ppm. The overall hourly average ammonia emission was calculated as 56.1 g/h.barn. Ammonia concentrations increased with lower airflow rate while ammonia emissions increased with higher airflow rate. As a result of this study, there is no significant relationship observed between ammonia emission and indoor environmental conditions such as temperature and relative humidity.