An instrument and method for applying thermal energy to targeted tissue. An instrument and method for tissue thermotherapy. In one embodiment, a method includes providing a vapor source comprising a pump configured for providing a flow of liquid media from a liquid media source into a vaporization chamber having a heating mechanism, actuating the pump to provide the liquid into the vaporization chamber, applying energy from the heating mechanism to convert a substantially water liquid media into a minimum water vapor level for causing an intended effect in tissue. For examples such levels can comprise at least 60% water vapor, at least 70% water vapor, at least 80% water vapor or at least 90% water vapor for causing an intended effect in tissue.