A mathematical model has been developed for calculating the heating effects of a laser beam on biological tissue. The model may be used for calculating the temperature rise and the extent of damage in tissue exposed to laser irradiation. It can be applied in conjunction with laser coagulation, laser surgery, laser hyperthermia, etc. We briefly describe the model and discuss its use for calculating temperature fields in lased tissue. Experimentally, we measured the temperature profiles in soft and hard tissue under nonablating conditions. The experimental results are in good agreement with the theoretical ones.