One of the significant odor sources on swine farms is manure storage. This study investigated reducing odor and gas emissions from a 29- x 39-m anaerobic swine lagoon by capturing gases beneath a 0.41-mm thick, flexible reinforced polyethylene membrane. The cover was anchored and sealed about its perimeter by burying the edges in a trench around the lagoon embankment. A fan installed alongside the lagoon drew gases continuously from a looped perimeter duct system to provide a (suction) pressure differential of approximately 500 Pa to hold the lagoon cover in place. The measured average emission rates of CO2, H2S, NH3, and CH4 were approximately 270 kg/ha-day, 92, 20, and 940 g/ha-day, respectively. The average flow rate from the suction fan was 0.194 m(3)/s (411 cfm) and average odor intensity was 598 OU/m(3). The derived odor emission rate was 116 OU/s. The total cost of the lagoon cover was $7,800 or $3.75/m(2) ($0.36/ft(2)). Operating cost was approximately $36/month, based on an electrical rate of $0.10 per kWh.