Odour associated with swine operations is from three main sources: (1) building exhaust, (2) manure storage, and (3) land application. However, odour from land application is becoming less of a concern as more and more swine producers are adopting manure injection. Odour emission from swine buildings is influenced by a number of factors, such as the type of operation, management practice, manure handling and storage, and ventilation. To develop odour control strategies, it is important to quantify odour emissions from each of the two main sources (buildings and manure storage). The first objective of this study was to quantify these relative odour contributions by comparing odour emissions between two similar swine operations with different manure storage systems – open and covered manure storage. This information will assist producers and regulatory authorities in making decisions on what to focus on, barns or manure storage, when adopting and recommending odour control technologies. It is estimated that agricultural operations contribute approximately 8% of the total greenhouse gas (GHG) emissions in 2002 in Canada, with about 49% of that originating from livestock production (Matin et al. 2004). However, little is known about the relative contributions to GHG emissions from barns and manure storage in swine production. The second objective of this study was to determine these relative contibutions. Odour and greenhouse gas (GHG) emissions were measured on two 3000-sow swine farrowing farms, one with open earthen manure storage (EMS) and another with negative air pressure (NAP) covered EMS. Air samples were taken in Tedlar bags with a vacuum chamber from exhaust fans of barns and the NAP EMS. A wind tunnel was used to collect air samples from the manure surface in the open EMS. Collected samples were analyzed for odour concentrations with a dynamic dilution olfactometer and for GHG concentrations with gas chromatography. It was concluded that the open EMS contributed 57% to the total odour emission from the operation; whereas the NAP EMS contributed only 2% to the total emission. The total odour emission from the farm with NCP EMS was 58% of that from the farm with open EMS. The CO2 emission rates from the building exhaust were significantly higher in the farrowing rooms than that from gestation rooms. Both CO2 and CH4 emissions from the secondary cell of the NAP EMS were negligible in comparison with the primary cell or with the open EMS. The CO2 emission rate from the primary cell of the NAP EMS was significantly lower than that from the open EMS. Although the CH4 emission rate from primary cell of the NCP EMS was not significantly different from the open EMS, the total CH4 emission from the NCP EMS was only 26% of that from the open EMS because the size of the primary cell of the EMS was small in comparison with the open EMS.