Abstract: Objective To compare the efficacy and safety of pulsed dye laser (PDL) and ultra-pulsed fractional carbon dioxide laser (UFCL) in treating hypertrophic scars after burns. Methods Two hundred and twenty one patients with hypertrophic scar after burns conforming to the study criteria were admitted to our unit from February 2015 to October 2017, and their data were retrospectively analyzed. Patients were divided into group PDL (n=122) and group UFCL (n=99) according to the treatment method. Patients in group PDL were treated with PDL once every 3-4 weeks. Patients in group UFCL were treated with UFCL once every 6-12 weeks. Patients in both groups were treated until 12 months after having scar. Scars were scored by Vancouver Scar Scale (VSS) before and after treatment. Patients′ pain was evaluated by Visual Analogue Scale (VAS) method before and after treatment. Blood flow in scar was monitored and recorded before treatment and in treatment months 6 and 12. Satisfaction degree of patients was recorded 3-6 months after treatment, and the satisfaction rate was calculated. Adverse reactions including duration of erythema/purpura, VAS in treatment, and loss of working time were recorded. Data were processed with one-way analysis of variance, t test, and Chi-square test. Results (1) VSS scores of patients in groups PDL and UFCL after treatment were significantly lower than those before treatment in the same group (t=11.34, 12.77, P<0.05). The decreasing VSS scores of patients after treatment in groups PDL and UFCL were (5.8±1.1) and (6.0±1.4) points, respectively, and there was no statistically significant difference between the two groups (t=1.91, P>0.05). (2) VAS of patients in groups PDL and UFCL after treatment were significantly lower than those before treatment in the same group (t=7.12, 5.23, P<0.05). The decreasing VAS of patients after treatment in groups PDL and UFCL were (4.0±0.6) and (3.2±1.3) points, respectively, and there was no statistically significant difference between the two groups (t=1.93, P>0.05). (3) Scar blood flow of patients in group PDL in treatment months 6 had no obvious change compared with that before treatment (t=1.59, P>0.05), while that in treatment months 12 significantly decreased compared with that before treatment and that in treatment months 6 (t=3.17, 6.96, P<0.05). Scar blood flow of patients in group UFCL in treatment months 6 significantly increased compared with that before treatment (t=6.01, P<0.05), while that in treatment months 12 significantly decreased compared with that in treatment months 6 (t=4.52, P<0.05), but had no obvious change compared with that before treatment (t=0.92, P>0.05). (4) The satisfaction degree of patients in group PDL was 80.3% (98/122), which in group UFCL was 76.8% (76/99), and there was no statistically significant difference between the two groups (χ²=0.97, P>0.05). (5) The duration of erythema/purpura of patients in group PDL was (5.2±0.7) d, significantly shorter than (6.1±0.5) d in group UFCL (t=2.49, P<0.05). The VAS of patients in group PDL during treatment was (1.9±0.9) points, significantly lower than (4.7±0.4) points in group UFCL (t=4.85, P<0.05). Loss of working time of patients in group UFCL was (9.17±0.72) d, which was significantly longer than (3.96±0.23) d in group PDL (t=3.17, P<0.05). Conclusions PDL and UFCL have definite effects on hypertrophic scar, while PDL with light pain, minor wound, and fast recovery time, is safe and effective for treatment of early hypertrophic scar and worthy of clinical promotion and application, especially for children and patients with poor pain tolerance.