Abstract Background: Acne scarring can lead to social and psychological distress. Objective: To compare the safety, efficacy, and long- term improvement of subcision using tri- beveled hypodermic (Th) needle versus cannula for the treatment of atrophic post- acne scars. Methods: Forty- six patients with atrophic post- acne scars were treated with subci- sion using (Th) needle on one side of the face and a blunt cannula on the other side of the face for 6 sessions one month apart. The primary outcome was based on the clini- cal improvement and patient satisfaction score. Skin biopsies were taken at baseline and 3months after the final session. Follow- up was 9 months. Results: Three months after the final session, a statistically highly significant differ- ence was detected in both sides from the baseline (p < 0.001). The overall improve- ment was 73.9% on the (Th) needle side versus 65.2% on the cannula side (p = 0.68). There was no significant difference in acne severity scarring grade between both sides (p = 0.86). The mean number of sessions was significantly less in the (Th) needle side (p < 0.001). Collagen deposition and reorganization were achieved with both modalities. Patient satisfaction showed no significant difference between both sides. The side effects were mild and significantly higher in the (Th) needle side (p = 0.001). Conclusion: Both modalities are effective and economic techniques. However, using a cannula is associated with much fewer side effects, more convenient for the patients and physicians compared to the (Th) needle.