Background: Keloid and hypertrophic scar are chronic skin disorders with significant psychosocial morbidity and symptoms of pain, pruritus and sometimes limitation of motion. Intralesional corticosteroid injection is the first-line treatment but its effect can be limited even with repeated injections. Based on our clinical experience, we devised a new method and named it “tunneling.” It improves drug delivery which may increase the efficacy of the medication. Objectives: The objective of this study was to evaluate the efficacy and safety of corticosteroid injection with tunneling compared to conventional injection method. Methods: A retrospective review was conducted on keloid patients treated with triamcinolone acetonide delivered intralesionally by conventional and tunneling methods. The treatment effect was evaluated 4 weeks after the first treatment was done. Clinical photos and medical records were reviewed using the Investigator Global Assessment (IGA) and Observer Scar Assessment Scale (OSAS). Statistical comparison of the results was performed using independent t-test. In addition, Analysis of Covariance (ANCOVA) was used to correct the effect of different concentration. Results: There was significant reduction in 2 scales compared with controls after 4 weeks of treatment. The difference was also significant after calibrating for different concentration of triamcinolone. Conclusion: Corticosteroid injection by tunneling method may be a more effective modality to treat scars.