A device for storing and delivering a sensor through a catheter. A sensor delivery device (10, 10') includes an elongate tube (20), which is attached to a rigid housing (22, 22'). A sensor (12), stored within a sterile environment comprising an interior of the sensor delivery device, has an attached signal line (16) that extends along the longitudinal axis of the delivery device and through its proximal end. The proximal end is open when the sensor is in its stored position. An eversible sheath (34) extends between the rigid housing and the signal line, sealingly separating the sterile environment (48) in which the sensor is stored from the open end of the rigid housing. To use the sensor, the signal line is moved into the rigid housing, causing the eversible sheath to turn inside out as the sensor is advanced through the catheter into its use position. The protection afforded by the eversible sheath permits the sensor to be withdrawn through the catheter and then reinserted without introducing contamination. A probe stop (54) abuts an inner surface of a catheter fitting (17), precisely controlling the distance that the sensor extends beyond a distal end of the catheter.