Dental implants are becoming increasingly important in prosthodontic rehabilitation. Bacterial infections, however, can induce bone loss and jeopardize clinical success. Recent literature has demonstrated that infrared CO(2) laser light is suitable for the decontamination of exposed implant surfaces. The aim of the present study was to investigate the influence of 308-nm excimer laser irradiation on peri-implantitis-associated bacteria in vitro. In this study, a XeCl excimer laser (308 nm) was used (Summit Technology, Boston, USA). Both aerobe (Streptococcus mutans, S. sanguis, Actinomyces naeslundii) and anaerobe microorganisms (A. odontolyticus, Prevotella melaninogenica) were tested. According to previous studies, a constant energy of 0.8 J/cm(2) and a constant frequency of 20 Hz were used for all irradiations. Colony-forming units after laser irradiation were counted. Excimer laser irradiation showed significant influence on the growth of all microorganisms. As compared to S. mutans and S. sanguis, A. naeslundii demonstrated higher sensitivity to laser irradiation. Anaerobe microorganisms, in contrast, demonstrated that a total of 200 pulses were sufficient to reduce the replication of these germs for more than 99.9%. Excimer laser irradiation (lambda = 308 nm) can significantly reduce both aerobe and anaerobe microorganisms. Depending on the parameters chosen, 200 pulses are sufficient for sterilization. New studies are necessary to evaluate if this wavelength is more of value in the treatment of peri-implantitis than other wavelengths or conventional therapies.