An artificial sphincter including an inflatable occlusion means for occluding a body passage, a stretchable fluid reservoir and a pump means. The pump means has a first port in fluid communication with the occlusion means and a second port in fluid communication with the fluid reservoir for selectively transferring an isotonic fluid from the occlusion means to said reservoir to deflate said occlusion means. The artificial sphincter further includes a pressure compensation balloon which is attached to the fluid reservoir and which, in use, is to be implanted in the abdomen of a patient.
