Swine production represents an important economic and social activity in Brazil, however, its traditional exploration is considered by the ambient institutions as an activity of great pollutant potential. The objective of this study was to compare ammonia level in the traditional slatted concrete floor system, a bedded system with wood shavings on top of the concrete floor, or a bedded system with rice hulls on top of the concrete floor. The study was conducted at the EMBRAPA Swine Research Station in Concordia, Santa Catarina, Brazil during August to November 2002. Significant differences among the treatments were observed; the concrete flooring system had the lowest ammonia levels, whereas both bedded systems shared fairly similar levels. However, these measured values in all the treatments were below the threshold level of 20 ppm.