Abstract: Method and apparatus for fracturing hard deposits such as urinary and biliary stones and atherosclerotic plaque in the human body. A flexible guide having a hard mass capping an end is adapted for insertion through a fluid passage in a living body. An energy source creates a rapid vapor expansion adjacent to the cap causing it to undergo a pulse like movement, imparting a high-velocity impulse to an adjacent deposit, thereby fracturing it. The energy source may be a laser with a fiber optic delivery system in the guide terminating adjacent to the cap to cause vaporization of the mass cap to create the vapor expansion. The energy source may be a spark generator with a conductor associated with the guide to deliver a fluid vaporizing spark adjacent to the mass cap. Other forms of rapid energy delivery such as chemical detonations or ballistic impact may also be applicable.