A safety trocar 10 is provided in which the cannula 14 is reciprocally mounted to the cannula housing 21 and reciprocates into the cannula housing 21 when a proximally directed force is applied thereto. The piercing tip 12 is maintaines in the exposed position by a latching mechanism 100 associated with the obturator shaft, and is automatically withdrawn into the cannula under the force of a spring 28 when the proximal force is removed from the cannula, the cannula thus advancing distally and releasing the latching mechanism. Penetration force is maintained at a minimum, and safe and efficacious trocar entry is facilitated. <IMAGE>
