Aged rodents demonstrate a difference in response to the stress of a novel environment compared to young rodents. Corticotropin releasing factor (CRF) is involved in both the hormonal and motor response to stressful stimuli. The contribution of CRF to age-related differences in behavior was investigated by assessing the response to intracerebroventricular (ICV) injection of CRF in old (27 month) and mature (10 month) C57BL male mice. Open field behavior was also observed. Old mice demonstrated less locomotion and less rearing than mature mice (p less than 0.01). ICV injection of CRF increased corticosterone compared to vehicle control (p less than 0.001) without an age-related difference. CRF decreased food consumption (p less than 0.001) in all animals but had no effect on locomotion (p greater than 0.3); no significant age-related differences were observed. These findings suggest that age-related differences in response to environmental novelty are not due to increased release of CRF.