A radial artery compression system comprising a radial artery compression device, the radial artery compression device adapted to allow a user to provide varying degrees of pressurization against a patient's radial artery to maintain a desired degree of hemostasis at a percutaneous access site, the radial artery compression device comprising: a body, the body comprising: a pump having a check valve, a pressure bladder, and a pressure control mechanism that can be activated to release fluid from the pressure bladder, thereby reducing a pressure in the pressure bladder, wherein the pump, the pressure bladder and the pressure control mechanism are disposed on a single plane and form a unit; and securing means to secure the body to the underside of a wrist of a patient in the area of the radial artery, such that the pressure bladder can be positioned adjacent the wrist of the patient; wherein the user activates the pump to inflate the pressure bladder between a first position and at least a second position to provide varying degrees of pressurization to the wrist of a patient in a manner that prevents blood from flowing out through an opening in the patient's radial artery to thereby achieve hemostasis at the access site; wherein when the pressure bladder is in the first position, the pressure bladder applies a first amount of pressurization against the wrist of the patient and when the pressure bladder is inflated to the second position by activation of the pump, the pressure bladder provides a second greater amount of pressurization against the patient's wrist than the first amount, and when the pressure bladder is deflated to a third position by activation of the pressure control mechanism, the pressure bladder provides a third amount of pressurization against the patient's wrist that is greater than the first amount of pressurization and less than the second amount of pressurization. a pump having a check valve, a pressure bladder, and a pressure control mechanism that can be activated to release fluid from the pressure bladder, thereby reducing a pressure in the pressure bladder, wherein the pump, the pressure bladder and the pressure control mechanism are disposed on a single plane and form a unit; and securing means to secure the body to the underside of a wrist of a patient in the area of the radial artery, such that the pressure bladder can be positioned adjacent the wrist of the patient; wherein the user activates the pump to inflate the pressure bladder between a first position and at least a second position to provide varying degrees of pressurization to the wrist of a patient in a manner that prevents blood from flowing out through an opening in the patient's radial artery to thereby achieve hemostasis at the access site; wherein when the pressure bladder is in the first position, the pressure bladder applies a first amount of pressurization against the wrist of the patient and when the pressure bladder is inflated to the second position by activation of the pump, the pressure bladder provides a second greater amount of pressurization against the patient's wrist than the first amount, and when the pressure bladder is deflated to a third position by activation of the pressure control mechanism, the pressure bladder provides a third amount of pressurization against the patient's wrist that is greater than the first amount of pressurization and less than the second amount of pressurization.