Abstract: Surgical apparatus which includes a waveguide, for example an optical fibre, through which laser energy is applied to tissues for such purposes as ablation of atheroma, destruction of calculi and lithotripsy. The optical fiber is provided with an end-piece through which it passes, and terminates flush with the distal end in the end-piece. For various applications at least the tip of the end-piece may be made either highly reflective or highly absorptive of the laser radiation. A balloon catheter may be fitted over the optical fibre. The end-piece may be provided with sensing means.