Due to the possibility of detecting certain physiological conditions from thermal features of the skin surface acquired from infrared thermal imaging, the health conditions of a person can be revealed by analyzing the thermal signatures of his or her forearms regions in an infrared image. The assessment of hand's or arm's temperature distribution for clinical diagnosis or monitoring requires the confinement of region of interest (ROI) on the forearms regions. Hence, the purpose of this study is automatically to segment forearms regions in an infrared thermal image so that the clinicians can able to locate the interested regions and extract the skin temperature distributions with a high degree of reproducibility.