Abstract Summary of trial design Treatment of depressed acne scars requires multiple modalities. Although needle subcision is a valuable method, it exhibits mild to moderate efficacy in treatment of deep acne scars owing to the high recurrence rate and other side effects. A total of 100 patients with rolling acne scars were randomly treated using the standard technique of 18 gauge cannula and 27 gauge needle subcision in two parallel groups, and the effect of cannula subcision instead of needle subcision was evaluated in the treatment of rolling acne scars