In this experiment, examined were short-term effect of alpha-2 adrenoreceptor agonist yohimbine on physiological, behavioral changes and ulceration induced by the 48 hr. conflict-stress session and compared with effect of conflict-stress condition. The experimental animals were 35 rats. each of which was distributes to one of the five group : yogimbine and conflict treatment group (experimental group N=10), conflict treatment without yohimbine group(control group N=10), yoked yohimbine without conflict group(compared group 1 N=4), yoked conflict without yohimbine group(compared group 2 N=4) and no stress treatment group(compared guoup 3 N=7). The experiment was conducted for 48 hours. During the first 24 hr. session, the animals received the feedback of ter shock termination or delay by their lever-pressing coping behavior so that could escape the stree stimulation. However, during the second 24 hr. conflict-stress session, they were provided a brief shock as a first feedback and the shock termination or delay as the second feedback of the lever-pressing coping behavior as in the first session. In this way avoidance-avoudance conflict condition was induced experimentally. Yohimbine(2cc/kg) was administrated twice during the entire experiment. Thus experimental group received the conflict stress and yohimvine, and control group took lnly conflict stress without yohimvine treatment. The compared 1 group which was yorked to experimental group which was yorked to control group took only uncontrollable stress without conflict, compared 2 group which was yorked to control group took only uncontrollable stress without yohimvine treatment and conflict, and compared 3 group did not receive any stress stimulation.