The role of olfactory cues in the Kamin Effect was examined. In one experiment, rats were trained to avoid shock and then tested for the avoidance response after retention intervals of up to 24 hr. Source and age of the stress-produced odors present at testing varied for six groups of rats. Rats tested after 6 hr but in the presence of odors aged 24 hr performed the avoidance response better than rats tested after 6 hr in the presence of odors aged 6 hr, even though under both conditions the odors present were produced by a different rat. Conversely, rats tested after 24 hr in the presence of odors aged 6 hr did not perform as well as rats tested in the presence of odors appropriate to the retention interval. Rats tested in the presence of odors from other rats, but appropriate to the retention interval, displayed the traditional Kamin Effect. A second experiment showed that odors aged within the range previously employed had no effect upon initial acquisition of avoidance. The results are consistent with a memory retrieval interpretation of the Kamin Effect, with stress-produced odorants serving as time-dependent cues for retrieval of memory of previous avoidance training.