A computer model can predict ammonia emissions if the number of urine puddles in a room is known. Seventy-two pigs were observed for 26 h at three different times during their grow-finish phase. Urination frequency was similar for males and females and did not change with age. The maximum number of events was between 12h00 and 20h00. Early morning events were rare. Emissions from the room cannot be directly linked to the urination pattern at this point, as puddles will emit ammonia for many hours.