Previous studies have indicated that glucocorticoids enhance memory consolidation, but their effects on memory reconsolidation are not clear. In this study, we studied the effects of corticosterone on memory reconsolidation in mice. Frothy mice were trained in a passive avoidance task. For memory reactivation, mice were returned to the chamber 48 h later. Immediately after reactivation, mice were injected with corticosterone (0.3, 1 or 3 mg/kg) or vehicle. Two, four, and seven days after memory reactivation, rats were returned to the context for 10 min, and step-through latency was recorded. The result showed that corticosterone at dose of 3 mg/kg impairs memory reconsolidation. Further, the results showed that corticotserone deficit was not reversed by a reminder shock. These findings indicate that post-reactivation administration of glucocorticoids impair memory reconsolidation.