As an alternative in endodontics to mechanical methods for root canal treatment, the use of a XeCl-excimer laser to prepare the canal wall was studied. In a light microscopic investigation undecalcified sections of laser-treated extracted human teeth showed that it was not possible to remove dentine in the root canal. Pulpal tissues remained in all wall areas. The available energy densities of this laser type seem to be not sufficient to ablate pulpal tissues or wall dentine.