Odour removal from liquid swine manure by subsurface flow constructed wetlands located in a greenhouse was quantified. The relationship between wetland treatments (planted vs. unplanted) and the concentrations of three malodorous compounds (dimethyl disulfide, ethyl acetate, and p-cresol) in wetland effluent were examined. A human sensory panel also evaluated wetland effluent odour. Experimental trials were conducted in a greenhouse to provide uniform environmental conditions year-round for wetland plants and microbes. Four subsurface flow wetlands planted with wetland grasses and four unplanted wetlands were loaded with liquid swine waste from a campus grower-finisher facility. The reduction of malodorous compounds in the liquid swine waste was quantified using gas chromatography. A human sensory panel ranked the offensiveness and intensity of wetland effluent using a cotton swatch technique. ANOVA revealed that mean concentrations of malodorous compounds were significantly lower in the planted wetland effluent ( alpha =0.01). On average, planted wetlands removed a higher percentage of malodorous compounds (60-80%) than unplanted wetlands (35-70%). Sign test analyses of odour panel data indicated that the median intensity level ranking ( theta ) was <=1 intensity level (IL) for planted and >1 IL for unplanted wetland effluent samples. In conclusion, planted wetlands outperformed unplanted wetlands at removing malodorous compounds from liquid swine manure and at producing wetland effluent that is neither intense nor objectionable to a human sensory panel.