Fluxes of atmospheric ammonia-nitrogen (NH3-N, where NH3-N=(14/17)NH3) from an anaerobic ~2.5 ha (1 ha=10,000 m2) commercial hog waste storage lagoon were measured during the summer of 1997 through the spring of 1998 in order to study the seasonal variability in emissions of NH3-N and its relationship to lagoon physicochemical properties. Ammonia-nitrogen fluxes were measured during each season (summer, fall, winter, and spring) using a dynamic flow through chamber system. Measured lagoon physicochemical parameters included surface lagoon temperature (Tl ¿C, ~15 cm below surface), lagoon pH, and Total Kjeldahl Nitrogen (TKN). The pH and TKN of the surface lagoon water ranged from 7 to 8 pH units, and 500 to 750 mg N L-1, respectively. The largest fluxes were observed during the summer (August 1997) (mean NH3-N flux=4017¿987 μg N m-2 min-1). Fluxes decreased through the fall (December 1997) months (844¿401 μg N m-2 min-1) to a minimum flux during the winter (February 1998) months (305¿154 μg N m-2 min-1). Emission rates increased during spring (May 1998) months (1706¿552 μg N m-2 min-1), but did not reach the magnitude of fluxes observed during the summer. Lagoon emissions in eastern North Carolina were estimated to constitute ~33% of total NH3-N emissions from commercial hog operations in North Carolina based on current inventories for NH3-N emissions published by the North Carolina Division of Air Quality, North Carolina Department of Environment and Natural Resources. The ammonia flux may be predicted by an observational model log10 (NH3-N flux)=0.048Tl+2.1. ¿ 2000 American Geophysical Union