It is well known that an emotionally arousing experience usually results in a robust and persistent memory trace and the expression of enhanced anxiety. The present study explored the potential mechanisms involved in the influence of a prior stressful event on the consolidation of a contextual fear memory and on the onset of anxiety-like behavior. An activation of ERK2 in basolateral amygdala (BLA) was evident twenty four hours after the stressful experience. Moreover, such environmental challenge facilitated memory formation and increased anxiety-like behavior. In addition, pretreatment with the intra-basolateral amygdala infusion with UO126 (MAPKinase inhibitor) prevents the stress-induced facilitating influence on fear memory formation and on anxiety-like behavioural.  Given that the activation of ERK1/2 pathway is essential for associative learning and the occurrence of anxiety, we propose that stress-induced facilitation of p-ERK2 in BLA is an important mechanism for the promoting influence of stress on both processes.