SYNOPSIS“Cold patches” in the external carotid territory previously have been described to have been associatedwith vascular‐related headaches. This study utilizes electronic thermography to examine the relationship.A sample of 275 patients diagnosed as having: vascular, scalp muscle contraction, cluster, post‐traumaticor psychogenic headaches, as well as 45 headache‐free individuals, served as subjects. Each subject wasadministered electronic thermography to determine if “cold patches” were present in the external carotidterritory. A “cold patch” was defined as a region more than 0.5°C cooler than the surrounding area.Chi Square analysis determined that vascular headache patients displayed a significantly greater number(p<.001) of “cold patches” than did normal individuals, or patients having scalp muscle contraction,psychogenic, or post‐traumatic type I headaches. Mixed headaches involving a vascular component alsodisplayed a significantly greater number (p<.001) of “cold patches,” as did cluster disorders (p<.001), andpost‐traumatic type III headaches (p<.001).This evidence supports a valid relationship between "cold patches" and vascular‐related headaches. It issuggested that the vascular “cold patch” be included as part of