Background and objective: Infantile hemangiomas (IHs) are benign lesions found in infants. Predicting the cosmetic outcome of these lesions is very difficult. Therefore, in this prospec- tive study, we assessed whether using an infrared thermometer (IRT) to measure the surface temperature of IHs would help to predict their proliferative potential.Materials and methods: Between January 2012 and March 2014, we prospectively investigated 103 children up to 6 months of age with a diagnosis of IH. None of them required immediate treatment. Two projection plain photographs of the IHs were obtained and the temperature of the IH surface was measured with the IRT at each visit. The IHs in these patients were divided into three groups: stable, slightly growing and growing IHs. We analyzed tempera- ture differences between the groups, relative operating characteristic (ROC) curves, and possible application of this method to clinical practice.Results: The median initial temperatures in the groups were 36.7 °C for the stable group, 37 °C for the slightly growing group, and 37.4 °C for the growing group (P < 0.01). The area under the ROC curve for the temperature values to predict growth was 0.929. Temperatures at or above 37.4 °C showed a specificity of 95%, a sensitivity of 75%, a positive predictive value 81%, and a negative predictive value of 95%.Conclusions: IRT is a time and cost effective tool, and is easy to learn. The surface tempera- ture of IH reflects its remaining growth potential and could be used in the outpatient setting for the evaluation and follow-up of IH.