An important non-spatial memory ability not well described in pigs is memory for objects. Knowledge of the robustness of object recognition memory in the pig, including when and how recognition fades, would be useful for pig producers using objects in an environmental enrichment program. While it seems clear that substrates for rooting are utilized by pigs for a greater duration and frequency than objects (Van de Weerd et al., 2006; Scott et al., 2006), and have a greater effect on welfare as indicated by decreased aggression and tail-biting (reviewed by Bracke et al., 2006), objects of all types can provoke some exploration (Van de Weerd et al., 2003). If pigs recognize a repeatedly encountered object as familiar, they would probably not interact with it as they would a novel object. Little is known, however, about how long a pig remembers objects. Therefore, it is the focus of this paper to address object recognition memory in the domestic pig. To better understand the effect of exposure time and delay intervals on pig object recognition memory, a modified spontaneous object recognition test was used to examine object recognition memory in the domestic pig. This test uses preference for a novel object over a previously encountered sample object as indicating recognition of the sample object, and no preference as indicating no recognition. We exposed 5-week-old pigs to different sample objects in their home pens for 10 min and 2 days, respectively. We tested for object recognition memory at various delay intervals after initial exposure by placing littermate pairs in a test pen for 10 min and recording snout contact with a sample object and a completely novel object. At a 1-h delay, half the pairs were tested with the 2-day sample object; the other half received the 10-min sample object. At a 3-h delay, pairs were tested with the opposite sample object. Pairs were also tested with the 2-day sample at a 5-day delay and the 10-min sample at a 6-day delay. We predicted that pigs would show a preference for the novel versus the 2-day sample object at all three delays, but would only prefer the novel object over the 10-min sample object at the 1-h and 3-h delays. Pigs did not show novelty preference in the presence of the 10-min sample object at any delay. Novelty preference in the presence of the 2-day sample object occurred at the 3-hour and 5-day delays, but not the 1-hour delay. The lack of novelty preference when pigs were tested with the 10-min sample object may have been due to failure to habituate to the sample object. Testing in a different location from the initial sample object exposure and retroactive interference from exposure to the 10-min sample object may have contributed to a temporary lack of novelty preference when pigs were tested with the 2-day sample object at the 1-h delay. The finding that pigs retained a memory for the 2-day sample object for at least 5 days suggests that restricting object exposure to less than 2 days may help to preserve the exploratory value of objects rotated among pens.