Gaseous ammonia emissions from livestock production are deemed responsible for the acidification of several ecosystems and for the formation of PM 2.5. The latter induces adverse health effects in humans, mostly respiratory ailments. In this study, ammonia emission rates from two tie-stall commercial dairy buildings were monitored in Canada where little data is currently available. Buildings studied were mechanically ventilated and livestock management practices were typical of Eastern Canada. Ammonia emission measurements made at building A during the months of February and March 2007 ranged from 3.77 to 6.80 g day −1 animal −1 while those performed at building B during summer 2007 ranged from 11.33 to 18.20 g day −1 animal −1. These values fall within the range of ammonia emission rates found in the literature for studies completed in Western Europe: 0.1625 g day −1 AU −1 to 23.38 g day −1 animal −1. A titration method, using acid traps, was used at building B to measure average ammonia concentrations while an electrochemical ammonia analyser was used at building A for continuous measurements. Propeller anemometers were developed to measure building ventilation flow rates. The precision of the equipment used to measure building ventilation rates and gaseous ammonia concentrations inside the building were evaluated at both locations.