Ammonia concentrations of exhaust air from a 960-head, High-RiseTM swine finishing facility and of air downwind from the facility were monitored during the facility’s first year in operation, 1998-99. Mean ammonia concentrations in exhaust air from three selected fans were 19.9, 15.6 and 18.1 ppm for their northwest, northeast and southeast fan locations, respectively, with an overall mean of 17.9 ppm for the 16-month study period. Concentrations of ammonia within the pig space (upper story) averaged 4.3 ppm and those within the lower story (manure storage area) averaged 21.8 ppm, over the same time period. All operating exhaust fans (from eight to twenty-two) were monitored for emissions over the final four months of the study. There was considerable variation in the ammonia concentrations of exhaust air from the total number of fans that were operating at any given time. The average mean concentration and standard deviation for the seven available sampling dates was 16.1 +or-11.6 ppm. Average ammonia concentrations within exhaust air from fans in northwest, northeast, southeast, and southwest quadrants were 18.5, 18.4, 13.5 and 12.6 ppm, respectively. Projected total ammonia emission rates for the sampling dates ranged from 4.1 to 59.0 g/min for the facility (6.2 to 88.5 g/day per pig space). Average ammonia concentrations were 16.1, 1.8, 0.3 and 0.1 ppm for the average fan exhaust, and for distances 3.0 m, 15.2 m and 30.5 m downwind of the facility, respectively.