Objective To explore the relationship between power density of He -Ne laser with the growth of fibroblasts in hypertroph ic scar (HS).Methods The cultured fibroblasts in HS were i rradiated with He -Ne laser(Wavelenth 632.8nm),various power densities such as50mW/cm 2 ,100mW/cm 2 and 150mW/cm 2 were respectively adopted once a day for 10minutes.After 1,3and 5times o f He -Ne laser for dose rate irradiation separatedly ,the cell count and cell circle analysis were counted and examined by trypa n blue staining and flow cytometry .Results The amount of cell after 1times of 50mW /cm 2 laser irradiation was markedly more than teh control(P<0.01).The amount of cells after 5times of 100mW/cm 2 ,3and 5times of 150mW/cm 2 laser irradiation was less than the controls(P <0.05).The result of cell circle analysis was corresponded with that of the cell count.Conclusion Both stimualtion and inhibition of He -Ne laser on the growth of scar fibroblasts can be obtained with vario us power densities.Power density of He -Ne laser associates with the effects on the growth of scar fibroblasts. Objective To explore the relationship between power density of He-Ne laser with the growth of fibroblasts in hypertrophic scar (HS). Methods The cultured fibroblasts in HS were radiated with He-Ne laser (Wavelenth 632.8nm), various power densities such as 50 mW / cm 2, 100 mW / cm 2 and 150 mW / cm 2 respectively respectively once a day for 10 minutes. After 1 and 3 times 5 times of He-Ne laser for dose rate irradiation separatedly, the cell count and cell circle analysis were counted by trypa n blue staining and flow cytometry. Results of the amount of cell after 1 × 50mg / cm 2 laser irradiation was markedly more than teh control (P <0.01). The amount of cells after 5times of 100mW / cm 2, 3 and 5times of The result of cell circle analysis was corresponded with that of the cell count. Confluence Both stimlation and inhibition of He-Ne laser on the growth of scar fibroblasts can be obtained with vario us power densities. Power density of He-Ne laser associates with the effects on the growth of scar fibroblasts.