Purpose: Differences in definitions of condition, relevant triggers, and the geographical locations of study centers, cause estimates of the prevalence of anaphylaxis to vary. Recent epidemiological data indicate that the incidence of anaphylaxis is rising. Methoda: to investigate the causes and clinical features of anaphylaxis in Korean adults, factors associated the severity of the condition, and serious outcomes, a retrospective medical record review performed on adult patients diagnosed with anaphylaxis between 2007 and 2011 in 15 university Hospital of South Korea. Results: A total of 1.806 cases (52% age 16-86 years) were reported. Cutaneous symptoms (84.0%), combined with respiratory (53, 9%) and/or cardiovascular (55.4%) symptoms, were the most frequent presentations. Using a recognized grading system, 1.776 cases could be classified as either mild, 340; moderate, 690; or severe, 746. Although eliciting factors varied significantly by age, gender, and regional and seasonal factors, drugs (46.5%; including nonsterodial ) anti-inflammatory drugs, antibiotics, and radiocontrast media) were the most common cause of anaphylaxis, followed by foods(24.2%), insect stings (16,4%), exercise (5,9%), and unknown etiology (7.0%). All age, multi-organ involvement, a history of allergic disease, and drug-induced anaphylaxis, were significant predictors of serious outcomes requiring hospital admission or prolongation of hospital stay. Epinephrine auto-injectors were prescribed for 74% of reported cases. Conclusions: The principal causes of Anaphilaxis in Korean adults were drugs, food, and insect stings. Drug-associated anaphylaxis, a history of allergic disease, multi organ involvement, older aged, were identified as predictors of serious outcomes.