Background and Objective: Considering the role of bacteria in causing some forms of acne, in recent years, the use of antibiotics along with other medications has had positive results in acne treatment; therefore, the present study aimed to compare the effect of the combination of topical erythromycin and zinc acetate with topical erythromycin alone in treating mild to moderate acne vulgaris. Materials and Methods: In this clinical trial, 76 patients with acne vulgaris who were referred to a specialized skin clinic were selected and randomly assigned into two treatment groups, namely, A (n=39) and B (n=37). Group A was treated with a local solution of erythromycin 4% without zinc acetate, and group B was treated with a combined local solution of erythromycin 4% and zinc acetate 1.2%. The treatment continued twice a day for three months. Results: In groups, A and B, respectively, the average lesion intensity score before treatment was 21.1 ± 6.5 and 21.9 ± 5.4 (P=0.555), the first month of treatment was 17.0 ± 6.4 and 15.7 ± 5.9 (P=0.578), the second month of treatment 9.1 ± 4.5 and 6.4 ± 3.3 (P=0.014), the third month of treatment 4.0 ± 3.0 and 2.0 ± 3.0 (P=0.001), and the frequency of complete recovery was 38.5 and 64.9%, respectively (P=0.021). In group B, the severity of papules in the second (P=0.002) and third (P=0.001) months of the treatment was significantly lower than in group A. Conclusion: Based on the obtained results, using a combination of erythromycin 4% with zinc acetate 1.2% as a topical solution is more effective than the topical solution of erythromycin 4% alone in treating acne lesions