An ultrasound catheter comprising: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen extending longitudinally therethrough; an ultrasound transmission member extending longitudinally through the lumen of the catheter body, the ultrasound transmission member having a distal end that is positioned at the distal end of the catheter body, and a proximal end that is connectable to a separate ultrasound generating device; a distal head mounted on the distal end of the catheter body, wherein the distal head has a generally rounded configuration, and has a proximal portion whose outer diameter is slightly less than the outer diameter of the distal portion of the distal head, so as to define an annular shoulder, wherein a distal end of a coil is attached to the annular shoulder, wherein a proximal end of the coil is attached to the distal end of the catheter body, the ultrasound transmission member being firmly held within a bore of the distal head, the ultrasound transmission member having a distalmost portion, an intermediate portion and a proximal portion, the distalmost portion, the intermediate portion and the proximal arranged in this order and being directly adjacent to each other, the distalmost portion having a larger diameter than the intermediate portion and the proximal portion having a larger diameter than the intermediate portion, the distalmost portion and the proximal portion having a substantially constant diameter, characterized by the intermediate portion being fully contained within the coil and having a length substantially equal to the distance between the distal end of the catheter body and the proximal end of the distal head. an elongate flexible catheter body having a proximal end, a distal end and at least one lumen extending longitudinally therethrough; an ultrasound transmission member extending longitudinally through the lumen of the catheter body, the ultrasound transmission member having a distal end that is positioned at the distal end of the catheter body, and a proximal end that is connectable to a separate ultrasound generating device; a distal head mounted on the distal end of the catheter body, wherein the distal head has a generally rounded configuration, and has a proximal portion whose outer diameter is slightly less than the outer diameter of the distal portion of the distal head, so as to define an annular shoulder, wherein a distal end of a coil is attached to the annular shoulder, wherein a proximal end of the coil is attached to the distal end of the catheter body, the ultrasound transmission member being firmly held within a bore of the distal head, the ultrasound transmission member having a distalmost portion, an intermediate portion and a proximal portion, the distalmost portion, the intermediate portion and the proximal arranged in this order and being directly adjacent to each other, the distalmost portion having a larger diameter than the intermediate portion and the proximal portion having a larger diameter than the intermediate portion, the distalmost portion and the proximal portion having a substantially constant diameter, characterized by the intermediate portion being fully contained within the coil and having a length substantially equal to the distance between the distal end of the catheter body and the proximal end of the distal head.