This study was performed to investigate on the frequent chief complaints and the causes of dogs and cats visiting to an emergency department, and to suggest the minimum requirements for veterinary emergency clinics in South Korea. The medical records were reviewed for 2,368 dogs and 347 cats visiting the emergency department of Haemaru Referral Animal Hospital from March 2012 to August 2013. Among them, 255 dogs and 35 cats visited more than one time and each visit was considered as an individual case. Therefore, 2,784 cases of dogs and 396 cases of cats were reviewed. The medical records were analyzed according to the criteria such as signalment, chief complaints, diagnoses, hospital admission, and outcome. In dogs, vomiting, diarrhea, or both were the most common chief complaints, followed by dyspnea, trauma, seizure, and lethargy. The most common causes of emergency visits were gastrointestinal disorders, followed by neurologic, cardiovascular, respiratory, urologic, and hematologic disorders. In cats, dyspnea was the most common chief complaint, followed by vomiting, diarrhea, or both, trauma, dysuria, and lethargy. The most common causes of emergency visits were urologic disorders followed by gastrointestinal, respiratory, infectious, and cardiovascular disorders. According to the results, vomiting, diarrhea, dyspnea, and trauma were the most frequently encountered chief complaints, which accounted for approximately 48.6% of all cases in both dogs and cats. However common causes were differed between the dogs and the cats. In order to provide proper emergency service, it is required to prepare the clinicians and facilities to diagnose and stabilize these emergency patients.