The present invention is directed towards a side port for an introducer sheath which precludes the inadvertent excursion a guide wire (or other article or material) through a side port while advancing through the main lumen of an introducer sheath. To prevent inadvertent excursions of a guide wire, the introducer sheath has one or more non-circular side ports. The non-circular component of the side port has a minimum transverse dimension that is smaller than the diameter of the guide wire to be introduced through the lumen of the introducer sheath. Therefore, the small diameter of the non-circular component of the side port prevents a guide wire from inadvertently entering the side port.