The devices of the present disclosure are rheolytic thrombectomy catheters with a self-inflating distal balloon. A self-inflating balloon is located distal to an inflow gap or orifice and distal to a fluid jet emanator, which self-inflating balloon is inflated and expanded by the utilization of internal operating forces consisting of forwardly directed high velocity fluid jet streams and/or entrained thrombus particulate therein. The self-inflating balloon, when inflated, impinges on the wall of the blood vessel to isolate sections of the blood vessel distal and proximal to the inflated balloon in order to prevent flow of thrombus particulate, fluids and the like distal to the self-inflating balloon and to provide a stagnant nonflow region proximal to the self-inflating balloon. The devices of the present disclosure also provide for a uniform spacing of the catheter tube with respect to the thrombus and/or wall of the blood vessel.