Atrophic acne scars (AAS) is one of the most common skin sequelae following acne vulgaris. Fractional laser has shown great therapeutic potential in recent years, while there is no standard of wound care after laser resurfacing. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a multifunctional cytokine, and has shown its value in many other acute wounds healing. In the present study, we investigated the efficacy and safety of topical recombinant human GM-CSF combined with 1927-nm fractional thulium fiber laser (TFL) in AAS treatment.