An improved splittable medical device introducer designed to introduce a medical device such as a lead or catheter, into a patient's vasculature without loss of blood or introduction of air is described. The introducer assembly is designed with a notch provided at the proximal end of the introducer housing. The notch, which may comprise a multitude of cross-sectional geometries, is designed to reduce the force required to separate the housing and the introducer sheath, thereby minimizing the possibility of unintentional dislodgement during separation. The notch also increases the repeatability and consistency of the amount of force required to separate the introducer housing and sheath.