Background: Alopecia areata(AA) usually presents with a few coin-sized bald spots. Even if AA is commonly diagnosed through history taking and physical examination without difficulty, there are other causes of hair loss simulating AA. Objectives: To identify other possible alopecic diseases, which are clinically similar to AA Methods: We investigated their final diagnoses of alopecia from 161 patients who had underwent skin biopsy between 2005 and 2018 to differentiate from AA due to clinical features of one to a few coin-sized alopecic patches. Chart review along with clinical photos and the results of skin pathology were carefully performed for accurate diagnosis. Results: Among 161 patients, AA(81 Patients, 50.3%) was the most common cause of alopecia. Lupus erythematosus(21 patients, 13%), trichotillomania(14 patients, 8.7%), epidermal cyst(7 patients, 4.3%), frontal fibrosing alopecia(3 patients, 1.9%), folliculitis decalvans(2 patients, 1.2%) and morphea(2 patients, 1.2%) were leading causes of localized alopecia, which clinically simulates AA in order. Conclusion: Even if AA is the most common cause of localized alopecia, other disease conditions including lupus erythematosus and trichotillomania can also present with similar features of AA. Since treatment modality, disease course and prognosis vary depending on diagnosed disease entities, dermatologists should be aware of other causes of localized alopecia mimicking AA through skin biopsy and careful history taking.