Since 1978, we have applied laser beams in hepatectomy in 15 patients. From 1980, we used a contactless YAG laser powered surgical probe. However, in view of the increase in the total accumulated energy, we have used, the laser scalpel to perform the operation despite the many drawbacks of this contact-type instrument. Since 1983, we have used the CO₂ laser with its superior separating effect. On this occasion, we have tried simultaneous high-output CO₂ YAG laser irradiation on an experimental basis, and comparison with the separate use of laser showed that serious, high-degree tissue change had occurred. It was also possible to observe very favorable results from the operation in clinical terms.