Résumé : A comparison of efficacy, safety and cost-effectiveness of lymecycline and minocycline in the treatment of acne vulgaris has been addressed. This was a multicenter, randomized, investigator-masked, parallel group trial involving patients with moderate to moderately severe acne vulgaris, receiving either lymecycline or minocycline for 12 weeks. Efficacy and safety evaluation was performed at baseline and at weeks 4, 8, and 12 and completed by a pharmacoeconomic analysis including week 12 data. One hundred and thirty-six patients were enrolled. At week 12, the mean percent reductions in inflammatory count were 63 % and 65 %, and for total lesions counts 58 % and 56 % for lymecycline and for minocycline respectively. Median percent reduction in non-inflammatory count were 54 % and 47 % for lymecycline and for minocycline respectively. Eighty-seven per cent of all patients tolerated the treatments well. Treatment with lymecycline was found to be 4 times more cost-effective than with minocycline. Results showed that lymecycline has a comparable efficacy and safety profile to minocycline while being 4 times more cost-effective.