The excimer laser-ArF has certain characteristics that render it ideal for the performance of stapedotomy. These include the short wavelength of the emitted laser beam (193 nm), its high water absorption rate, the ability of pin-point focusing and its capability of operating in a pulse mode. In an effort to measure the temperature changes of the labyrinthine fluids in the inner ear during excimer laser irradiation, a cochlear model with the dimensions of the normal vestibule was designed. In this model cerebrospinal fluid (CSF) was used as a substitute for the labyrinthine fluids. Our study showed that the number of pulses needed to created the stapedotomy fenestra to the bony plate were 112-132. The temperature elevation of the CSF during laser irradiation showed only a slight increase of 0.1-0.4°C. The results of this study are very encouraging for the future use of the excimer laser in clinical situations. © 1993 Baillière Tindall.