Résumé : Introduction: Literature has shown that recommendations linked to isotretinoin concerning teratogenicity are poorly followed. One of these recommendation is the use of at least one effective method of contraception one month before, during and one month after the treatment. The aim of this study is to evaluate the concomitant use of contraception and isotretinoin, and to measure medication adherence to isotretinoin and contraception with pharmacy refill data.Methods: Medication adherence was measured according to the Medication Possession Ratio (MPR) for patients with at least two prescriptions. Influence of sex and age on adherence was analyzed with the Mann-Whitney test and the Spearman coefficient correlation using STATA®. Concomitant use of contraception and isotretinoin was analyzed with descriptive statistic using Excel. Reimbursed prescription data for all patients in Belgium were received from Pharmanet – INAMI from January 2012 to August 2015.Results: MPR was higher than 80% for 62.9% of patients receiving isotretinoin (n = 63 251, 47.8% of women), 71.8% of women taking oral contraceptives (n = 11 343), 71.1% of women with contraceptive rings (n = 242), and 77.4% of women with contraceptive patches (n = 58). Men seems more adherent to isotretinoin than women (69.3% vs 63.1%, P = 0.0000). Influence of age on adherence was very low (rs-isotretinoin = -0.15 - P = 0.0000, rs-oral contraception = -0.14 - P = 0.0000, rs-rings = -0.08 - P = 0.7302 and rs-patches = -0.05 - P = 0.1782). Among women taking isotretinoin between 12 and 21 years old, 63.5% received at least one contraception prescription. However, 15.6% of women fully respected the use of contraception one month before, during and one month after the treatment. Conclusion: Although about three-fourths of patients are adherent to isotretinoin and contraception, about 85% of women in childbearing age don’t follow the main recommendation.