Background Acne vulgaris of adult woman has increased over the past 10 years; it affects currently 20 to 30% of adult women. The physiopathology of adult woman acne is distinguished from the teenager one essentially by 2 factors: hormonal one with a peripheral hyperandrogeny coupled with an hypersensibility of cutaneous androgens receptors and an inflammatory one linked with Cutibacterium acnes. On a therapeutic plan, in female acne, four types of systemic treatment, approved in this indication are: cyclines which are problematic for the bacterial resistance; zinc salts which target only the inflammatory lesions and are less effective as cycline; antiandrogens, with acetate of cyproterone associated with risks of phlebitis and pulmonary embolism and recently meningioma. The last alternative is represented by isotretinoin but the use in women of childbearing potential is binding because of the teratogen risks and in addition, peripheral hyperandrogenia represents an identified risk of relapse. In this context, the spironolactone could represent an interesting alternative. It blocks the 5-alpha-reductase receptors at sebaceous gland and inhibits LH production at the pituitary level. It has not isotretinoin constraints, does not lead to bacterial resistance and targets the peripheral hyperandrogenia. Currently, very few studies have been performed on a weak number of patients. They showed that at low doses (lower than 200mg/day), spironolactone can be effective against acne. Methods: In that context, it seemed clearly interesting to perform the first double-blind randomized study spironolactone vs cyclines, which remains the moderate acne reference treatment and to demonstrate the superiority of spironolactone’s efficacy in order to establish it as an alternative way to cyclines. Discussion: Acne’s treatment frequently used in female acne is systemic antibiotics with many courses as it is a chronic inflammatory disease. In the context of recent WHO revelation about serious, worldwide threat to public health about antibiotic resistance, this trial could permit to give to the physician another alternative in adult female acne before using isotretinoin whose management is more complex. Trial registration : On ClinicalTrials.gov, registration number NCT03334682, first published on 7 November, 2017. Recruitment is still ongoing. Keywords : acne vulgaris, spironolactone, cycline