Objective To explore the relationship between blood perfusion and pulsed dye laser(PDL)effectiveness of port-wine stains(PWS)on extremities.Methods Patients with untreated PWS on extremities were selected.Blood perfusion of the selected sites on both proximal and distal limbs as well as control sites was detected by laser speckle image(LSI)before treatment.Then the patients were treated with PDL for 3 sessions in total.After 3 months of treatment,the therapeutic effect was evaluated,and the relationship between blood perfusion and therapeutic effect was analyzed.Results Nineteen patients were included,17 on upper limb and 2 on lower limb.The mean Speckle Flow Image(SFI)value of the PWS on upper arm/thigh was significantly lower(80.51 ±16.96)PU than the SFI on hand/feet(155.68 ±71.86)PU.According to photometric evaluation and VAS score,the PDL efficacy on proximal limbs was significantly better than distal limbs(P<0.05).Significant correlations existed between blood perfusion and PDL efficacy(r=-0.351,P=0.031).Conclusion PWS on the proximal limb responds better to PDL,compared with PWS on the distal limb.This variation in efficacy may attribute to differences in blood perfusion.