In this prospective study, it was aimed to survey the incidence of untoward reactions and overall problems occurred when iodinated contrast media was used for the purpose of diagnostic radiology. So, the causes of adverse reactions to the contrast media in 34 patients were analyzed from 474 cases, and the following results were obtained : 1. The incidence of adverse reactions were noticed in 34 cases among 474 cases. (7.15%) 2. Positive allergic history or previous examinations was not related to present examination statistically. 3. The erythema, less than 2mm in diameter after skin test was not paralleled with the occurrence of side reaction, but when over 5mm, it was significantly associated with the reaction. 4. The incidence was neither related to sex or age, but the frequency was especially lower in person, below 20 years of age. 5. The frequent symptoms and signs in side reactions were chilling (24.5%), nausea (22.6%), and flushing (15.1%) 6. The dosage of Hypaque or dorray had correlation with the incidnece of side reactions, but Urografin and Biligrafin did not. 7. Patients experiencing fear and anxiety did not show any relationship in the incidence of adverse reactions.