The morphometrical analysis of the effect of a pulsed CO2 laser on in vitro fresh rabbit vessel tissue was performed. The laser energy was delivered through a silver-halide fiber and the real time temperature was monitored via a second silver-halide fiber positioned on the external side of the irradiated tissue sample. In addition, a mathematical model was identified and applied on the analysis of the samples to quantify the internal temperature distribution. The model takes into account the dimension (coagulation, vacuolization) and the speed of the receding boundary between the ablated and normal tissue in a pulsed beam mode. Superficial hystological lesions were observed with ranges of energies of 20 msec/pulse, 1 Hz, 2 Hz, at 100 mJ, corresponding to a measured maximal external temperature range between 50 degree(s) and 60 degree(s)C. The used mathematical model has shown good agreement with these experimentally collected temperature measurements. Higher repetition rates for both 33 and 100 mJ/p were found to produce crater formation, in all the samples. The correspondent measured external temperatures were between 55 degree(s) and 95 degree(s)C and the calculated internal temperature of the injured layers were 142 - 306 degree(s)C, corresponding to the carbonization zones and depending on the type of tissue. The morphometrical analysis have shown: the CO2 laser effect on the tissue is dependent on the angle of irradiation, the stereo metrical configuration and the water content of the irradiated tissue. A threshold value for injury generation is proposed.