Anaphylactoid reactions to radiocontrast material(RCM) administration are significant clinical problem not only because the pathogenesis of such reaction has not been elucidated but also because anaphylactoid reaction to RCM occur with significant frequency in patients who have experienced previous reaction and who must be given RCM again. The pretreatement protocols and provocative challenge test have been instrumental in reducing both frequency and severity of side reaction in high risk patients. We present here 2 cases of severe anaphylacoid reaction to radiocontrast material (Hytrast) during bronchogram and review literatures briefly.