The air quality in 82 German livestock buildings was investigated, using ammonia as a gaseous indicator. The ammonia concentrations were measured hourly and a 24 h mean was calculated. In cattle houses the mean ammonia measurement ranged between 3·7 ppm in calf houses (n = 16), 4·7 ppm in beef units (n = 10) and 6·4 ppm in dairy cattle houses (n = 8). In pig buildings the highest mean concentrations of 15·9 ppm were found in fattening pig livestocks (n = 8). In sow (n = 16) and weaner livestock buildings (n = 8) the averaged ammonia concentration varied between 13·4 ppm and 9·1 ppm, respectively. Within poultry houses, broiler flocks (n = 8) were associated with ammonia concentrations of 21·2 ppm. On the other hand, livestock buildings containing laying hens (n = 8) showed the lowest ammonia concentrations of all, namely 2·7 ppm. A significant positive correlation between temperature, relative humidity and ammonia concentrations could be found in poultry houses. Assuming an ammonia threshold limit value of 15 ppm, although no cattle house in this study exceeded this recommended limit, 31% of all the pig and poultry units investigated did, indicating a need for improved housing conditions in the future.