Background: Systemic corticosteroids can arrest the progression of alopecia areata and lead to hair growth in a significant proportion of patients but may also cause unacceptable side effects. Objective: To minimize the side effects, we tried a new approach using minipulse therapy with betamethasone (CelestoneR). We performed a clinical observation of alopecia areata to understand its therapeutic responses. Method: Forty six patients with alopecia areata were given 3mg betamethasone as a single oral dose on 2 consecutive days per week. Therapeutic effects and side reactions were evaluated by dermatologists every month. Results: The extent of hair regrowth varied in different patients and even in different lesions in the same patient. Effective response, which shows vellus and/or terminal hair growth for more than 1 month, was achieved in 67.4% of the patients (31 cases). The side effects included acne in 14 patients, weight gain in 11 patients, gastrointestinal discomfort in 6 patients and facial flushing or edema in 5 patients; 19 patients had no side effects. Conclusions: Oral minipulse therapy with betamethasone seems to be an effective treatment modality to arrest the progression of alopecia areata and also induces hair regrowth. This modality of treatment had minimal and less severe side effects, compared with currently used pulse therapy with methylprednisolone. It deserves to be tried on a large scale to evaluate its advantages and disadvan-tages over the currently useful methods of treatment. (Korean J Dermatol 2001;39 (7) 775-781)