Recent clinical experience using the neodymium-YAG laser for the ablation of superficial bladder carcinoma seems to indicate a decreased local and second-site recurrence rate when compared to standard electrosurgical methods. Altered tumor cell implantation has been suggested as a mechanism explaining this phenomenon. The purpose of this study was to compare the effects of laser ablation and standard electrosurgical resection on tumor implantation. Each of three requisite steps in tumor cell implantation was assayed in an animal model system. The number of viable tumor cells liberated during ablation of a standardized lesion was 620% greater in the electrosurgically resected group compared to the laser irradiated group. No difference was observed in the qualitative or quantitative patterns of cellular adherence to a fulguration bladder injury compared to a laser bladder injury. The number of cells adhering to an injury site was shown to increase as a function of the cell concentration to which it was exposed. There was no difference between groups in occurrence of tumor at the injury site following exposure to an equal number of tumor cells. This study has demonstrated marked differences between electroresection and laser ablation in terms of the number of viable cells released during the course of tumor removal. This data, together with the absence of injury site differences, suggests it may play a role in the clinically observed differences in tumor recurrence rates.