The aim of this paper was to evaluate efficacy and tolerability of a topical gel (ACNAID TM gel medical device) containing 3% hydrogen peroxide (HPO), 1.5% salicylic acid (SA) and 4% D-panthenol (D-p) in the treatment of mild-moderate acne, comparing it with a previous formulation (ACNAID TM gel Cosmetic) containing 4% HPO, 0.5% SA, 4% D-p.Twenty patients of both sex with mild-moderate acne have been selected. The topical gel was applied twice a day for 60 days. Evaluations included: Global Acne Grading System (GAGS); lesions count; photographic assessment; a questionnaire to assess the tolerability. The results have been compared with those obtained in a previous study conducted with the formulation containing 4% HPO, 0.5% SA, 4% D-p.The GAGS score showed a reduction of 43% from T0 to T1 and of 61% from T0 to T2. Count of lesions: comedones reduction of 62% from T0 to T1 and of 95% from T0 to T2; papules reduction of 49% from T0 to T1 and of 68% from T0 to T2; pustules reduction of 75% from T0 to T1 and of 100% from T0 to T2. Digital images showed a significant reduction of acne lesions. At T2 the tolerability of the topical product was excellent according to 83% of patients and good according to 17% of patients.The topical gel has demonstrated to be effective and safe for treatment of mild to moderate acne. No patients reported side effects. These results are superior to those obtained in the previous study.