A double-blind, half-side comparative dermal atrophy study of fluocortin butylester 0.75% clobetasone butyrate 0.05%, hydrocortisone acetate 1% and placebo creams was carried out in 29 healthy human male volunteers. Skin thickness was measured by a modified radiographic technique before and after an 8-week application period of the test preparations. Significant skin thinning occurred in 3 of the 10 subjects treated with clobetasone butyrate and atrophy of marginal significance in 1 of the 29 subjects treated with fluocortin butylester. The results suggest that, compared with other fluorinated topical steroids, fluocortin butylester 0.75% is unlikely to produce significant dermal atrophy when used in the short and medium term.