The invention relates to a pressure sensor catheter and method for measuring pressure on a distal side of a flow constriction, such as a stenosis, in a body lumen or measuring a pressure difference over the flow constriction. The catheter includes a pressure transfer tube for passing through the constriction, the tube being connected to and extending from a pressure sensor for transferring the pressure at the distal side of the constriction via the tube to the sensor, and a catheter body for introduction of the catheter into the body lumen, wherein the catheter body comprises the sensor at a sensor position, such that the sensor in use is positioned in the body lumen, and wherein a distal end region of the catheter including the distal end region of the pressure transfer tube has a smaller maximum outer diameter than the outer diameter of the catheter at the sensor position.
