Background: Adverse cutaneous drug reactions (ACDRs) are common and are responsible for increased morbidity, mortality, and socioeconomic costs. Objective: The purpose of our study was to investigate the common drugs and clinical patterns related to ACDRs using an electronic drug adverse reaction reporting system at a single secondary referral center. Methods: We conducted a retrospective analysis of the ACDR database between January 2014 and April 2016 at the Ilsan Paik Hospital. Results: The study analyzed 320 patients with ACDRs (male：female ratio=93:227; mean age 50.8±17.8 years). Using a Korean causality evaluation algorithm, the percentage of drugs with a possible relationship with ACDRs was calculated to be 50.6%, while the percentage with a probable relationship was 44.7%. Antibiotics (44.0%), radiocontrast media (15.1%), and non-steroidal anti-inflammatory drugs (NSAIDs) (14.3%) were the most commonly implicated drugs. Antibiotics, including cephalosporins (30.6%) and quinolones (10.2%), were responsible for the majority of the ACDRs. Acetic acid (5.9%) and propionic acid (5.9%) derivatives of NSAIDs were also common causative agents. The most common clinical presentations were maculopapular exanthema (33.4%), pruritus (30.9%), and urticaria (25.7%). Severe ACDRs were significantly associated with older age, eosinophilia, and underlying heart and renal diseases (p＜0.05). Conclusion: Antibiotics, radiocontrast media, and NSAIDs were identified as common causes of ACDRs. Older age, eosinophilia, heart disease, and renal disease were associated with severe ACDRs. (Korean J Dermatol 2018;56(4): 251∼258)