A multiwavelength laser system designed for precise and efficient tissue ablation under water was realized by simultaneously coupling radiation of a holmium:YAG laser, emitting at a wavelength of 2.12 &mgr;m and an erbium: YSGG laser at 2.79 &mgr;m into the same zirconium fluoride (ZrF4) fiber. The beam paths of the two lasers were collinearly combined taking advantage of the dispersion of an Infrasil prism. Fast video flash photographs and laser induced pressure transients simultaneously recorded with a PVDF pressure transducer were used to study the dynamics of bubble formation at the submerged fiber tip. The bubble size and the bubble lifetime were determined as a function of the wavelength and the delay time between the two different laser pulses. The results indicate that the combination of 2 and 3 &mgr;m radiation takes specific advantage of both wavelengths and strongly enhances the ablation efficiency of tissue under water. ©1995 American Institute of Physics.