Background: Rosacea is characterized by erythema of the face that persists for several months or longer. Rosaceais usually diagnosed based on clinical presentation and a biopsy is rarely performed for diagnostic purposes. However,a biopsy may be helpful when the symptoms are atypical. Objective: We identified commonly appearing histological characteristics of rosacea such as inflammation, sebaceoushyperplasia, granulomatous reaction, epidermal hyperplasia, Demodex, pustules, and fibrosis. In addition, we evaluatedthese according to clinical subtype. Methods: We examined the histological findings of 200 rosacea patients who visited our hospital. Histologicalfindings were evaluated according to clinical subtype. The standard classification and staging method published bythe National Rosacea Society was used for clinical classification. Results: The erythematotelangiectatic and papulopustular types of rosacea were the most common. Mild inflammationwas found in 56.0% of the patients (1 and 1＋) and 49.0% showed inflammation greater than 2 degrees. Themost commonly observed histological features across all subtypes were sebaceous hyperplasia followed by epidermalhyperplasia and Demodex. However, sebaceous hyperplasia and Demodex were not observed in ocular rosacea. Conclusion: Some histological findings such as inflammation, granulomatous reaction, sebaceous hyperplasia,pustule, Demodex, epidermal hyperplasia, and fibrosis were commonly observed in rosacea. There were no distinctivesubtype-specific characteristics, but various histological characteristics were observed in a single clinical subtype. (Korean J Dermatol 2015;53(1):30∼37)