Background/purpose: Conventional treatment methods for acne vulgaris have various side effects such as the development of bacterial resistance, phototoxicity, vertigo, gastro-intestinal problems, and drug eruptions. To minimize such side effects, light and thermal methods have been alternately suggested. This study characterized a new acne vulgaris treatment device (AVTD) that combines both light and thermal methods and evaluated its clinical efficacy. Methods: We characterized the thermal and light properties of the AVTD itself and evaluated its thermal characteristics in ex vivo porcine skin samples. The Arrhenius equation was used to calculate the skin thermal injury coefficient to confirm the skin safety of the AVTD. Finally, the clinical efficacy of the AVDT was evaluated by analyzing cross-polarization and erythema index images, which were obtained from 13 volunteers undergoing treatment with the AVTD. Results: The temperature of the AVTD itself was maintained at 49.1°C on the tip and 39.7°C in the porcine skin samples. The peak intensity of the light-emitting diode (LED) light was observed at 468nm. The skin safety of the AVTD was confirmed and 84.2% of the volunteers presented positive treatment results. Conclusion: The treatment of acne using the AVTD resulted in a high treatment rate in a clinical study, minimizing side effects. On the basis of these results, we can be sure that the AVTD may be effectively used for the treatment of acne vulgaris. © 2011 John Wiley & Sons A/S.