A non-sheath based medical device delivery system is provided including an elongated tubular guide body having a distal end fixedly attached to a resilient collet with a longitudinal opening to receive a medical lead or other device. The collet may be opened by actuating a retraction member to cause the closing member to slide proximally along the collet shaft, allowing the collet to maintain a normally open position. With the collet closed, the device may be advanced to a desired internal body location by advancing the guide body. The majority of the device body will be exposed, running alongside the guide body, allowing any sensors or electrodes located on the device body to be fully operational during the implantation procedure. The delivery system may be removed by opening the collet, to slidably disengage from the device body.