BACKGROUND: Hypertrophic scars are devastating outcomes of severe burn injuries, producing physical and mental burdens. Adequate treatment is of benefit to relieve these burdens. Laser therapy has shown scar reducing effects. In this study, we compared outcomes after combination of two different lasers or single laser treatment to treat severe hypertrophic burn scars. METHODS: Forty patients with hypertrophic burn scars were included in one of two therapeutic groups: continuous wave CO laser and fractional ablative CO laser group (group 1, n = 20) or fractional ablative CO laser alone group (group 2, n = 20). Hypertrophic scars were evaluated by the observer-rated Vancouver Scar Scale (VSS) before and after treatment and by patient-completed questionnaires after treatment. Comparative analyses were performed before and after treatment, and time-dependent improvement was also analyzed. RESULTS: Forty patients (54 hypertrophic scars) completed the laser treatment protocols. Group 1 exhibited significantly more improvement in VSS vascularity, pliability, and height indices than group 2 (p < 0.05). Time-dependent analysis of total VSS scores suggested that group 1 experienced more improvement during a shorter treatment period (p < 0.05). For patient-reported outcomes, group 1 noted better grades than group 2 in four indices, namely scar appearance, scar thickness, pain, and pruritus (p < 0.05). CONCLUSION: Effective scar reduction was achieved using combination laser treatment, with significant improvement in multiple observer- and patient-reported outcomes. The shorter treatment period of the combination method can be a merit, as prolonged hypertrophic scars may increase morbidity. Nonetheless, cautious treatment protocols are necessary to avoid undesirable sequelae related to laser application.