In Seoul City, the rate of households with a cat or dog was 17.9%, and the number of households with a companion animal was estimated to 3,590,000 in 2013. But, In Seoul City, more than 13,000 animals are abandoned every year. In this study, the occurrence, monthly population change, breed, sex, age, and health condition of abandoned dogs and cats in each district of Seoul City in 2013 were surveyed based on data obtained from the website of the Animal Protection Management System, Animal and Plant Quarantine Agency (www.animal.go.kr). In 2013, out of 11,320 abandoned animals in total, 7,772 (68.66%) were dogs and 3,548 (31.34%) were cats. Regarding dogs, 5,450 (70.12%) were purebred and 2,322 (29.88%) were crossbred; 5,279 (67.92%) were in normal health condition and 2,493 (32.08%) were in abnormal health condition; and 3,473 (44.69%) were 0-2 years old.