Odor emission rates and characteristics were evaluated at two commercial swine nurseries in Indiana during the months of March, April and May. The nursersies housing 94 to 250 pigs were mechanically ventilated with long term manure pit storages under a wire floor. Incoming ventilation air at one of the nurseries was tempered in a heated hallwaay. An eight member odor panel evaluated odor concentration with a dyanamic olfactormeter and odor intensity and hedonic tone at full strength. The odor concentration of incoming ventilation air ranged from 7-85 odor units per cubic meter and averaged 18 units. It ranged from 94 to 635 and aeraged 190 odor units in ventilation exhaust air. The mean odor emission rates of the two nurseries rates were 18.3 and 62.5 odour units respectively.