A balloon guide catheter assembly for insertion and positioning of therapeutic devices within a vascular system, the balloon catheter assembly comprising: a tubular outer member having a proximal portion, a distal portion, and an outer member lumen extending there between, wherein the outer member lumen is in communication with a distal opening of the outer member; a tubular inner member having a proximal portion, a distal portion, and an inner member lumen extending there between, wherein the inner member lumen is in communication with a distal opening of the inner member; a balloon member having respective proximal and distal ends (48, 50) secured to and circumferentially around an outer surface of the distal portion of the outer member such that an inner surface of the balloon member and the outer surface of the outer member define an inflatable balloon interior; and a tubular seal being arranged at the distal portion of the outer member, wherein the seal is configured to form a fluid tight seal between the inner surface of the outer member and the outer surface of the inner member in a sealing position of the outer member and the inner member, the inner member is at least partially disposed in the outer member lumen such that an outer surface of the inner member and an inner surface of the outer member together define an annular fluid path, the outer member comprising a wall having one or more passages therethrough that form a fluid pathway between the annular fluid path and the balloon interior, and wherein the tubular seal is arranged distal to said one or more passages and has a proximal seal portion and a distal seal portion, and the proximal seal portion being arranged circumferentially around the inner surface of the distal portion of the outer member and having a tapered inside surface which tapers inward from the proximal end of the proximal seal portion to the inner most part of the seal, and the distal seal portion being arranged on the distal end of the outer member, wherein the inner member is movable relative to the outer member in longitudinal direction from a non-sealing position, in which the distal portion of the inner member is positioned proximal of the seal such that a fluid communication exists between the distal opening of the outer member and the annular fluid path, and the sealing position, in which the distal portion of the inner member contacts the seal thereby sealing the annular fluid path at said distal seal portion. a tubular outer member having a proximal portion, a distal portion, and an outer member lumen extending there between, wherein the outer member lumen is in communication with a distal opening of the outer member; a tubular inner member having a proximal portion, a distal portion, and an inner member lumen extending there between, wherein the inner member lumen is in communication with a distal opening of the inner member; a balloon member having respective proximal and distal ends (48, 50) secured to and circumferentially around an outer surface of the distal portion of the outer member such that an inner surface of the balloon member and the outer surface of the outer member define an inflatable balloon interior; and a tubular seal being arranged at the distal portion of the outer member, wherein the seal is configured to form a fluid tight seal between the inner surface of the outer member and the outer surface of the inner member in a sealing position of the outer member and the inner member, the inner member is at least partially disposed in the outer member lumen such that an outer surface of the inner member and an inner surface of the outer member together define an annular fluid path, the outer member comprising a wall having one or more passages therethrough that form a fluid pathway between the annular fluid path and the balloon interior, and wherein the tubular seal is arranged distal to said one or more passages and has a proximal seal portion and a distal seal portion, and the proximal seal portion being arranged circumferentially around the inner surface of the distal portion of the outer member and having a tapered inside surface which tapers inward from the proximal end of the proximal seal portion to the inner most part of the seal, and the distal seal portion being arranged on the distal end of the outer member, wherein the inner member is movable relative to the outer member in longitudinal direction from a non-sealing position, in which the distal portion of the inner member is positioned proximal of the seal such that a fluid communication exists between the distal opening of the outer member and the annular fluid path, and the sealing position, in which the distal portion of the inner member contacts the seal thereby sealing the annular fluid path at said distal seal portion.