Sensor guide wire for intravascular measurements of a physiological variable in a living body, comprising a core wire running along at least a part of the sensor guide wire and a sensor element arranged in a jacket in a sensor region of the sensor guide wire. The jacket is tubular and is provided with a jacket wall and a portion of the core wire that extends longitudinally along the sensor region forms part of the wall of the jacket, in order to provide more space in the jacket.