Laser angioplasty has a great potential as a possible alternative to the conventional methods in the treatment of occlusive vascular diseases. This thesis has been advocated to get a better understanding of the interaction of excimer laser radiation with vascular tissue and to define the possible solutions of the problems of vascular perforation and thermal damage. Xenon Chloride (XeCl) and Krypton fluoride (KrF) excimer lasers operated at 308 nm. and 248 nm.wavelengths respectively were applied on 317 normal and atherosclerotic aorta samples. This study shows that both types of lasers are able to ablate normal and atherosclerotic tissues with extreme precision and controllability. Limited thermal effect is detected around the crater's border induced by the application of laser radiation. The extent of which depends mainly on the applied wavelength. For both lasers, the dose-response relationships revealed a direct correlation between etch rate and applied energy. This relationship is non-linear for XeCl laser. Histological study indicates that thermal process has a synergistic action with the photoablative process during tissue ablation at high energy levels, it also Indicate that increasing the repetition rate cause more thermal injury at this wavelength. The dose-response relationship for KrF laser is linear. Histological study revealed minimal thermal injury, which is not affected by the repetition rate,, indicating that a; photoablative process is acting mainly during tissue ablation at this, wavelength. In this study the ablative thresholds are less than those recorded in previous studies, however the ablative threshold is higher at the longer wavelengths Selective ablation for atherosclerotic plaques can't be achieved neither by XeCl nor KrF lasers. This study suggests that 308 run. laser beam at repetition rate of 10 Hz. and energy level around 500 mJ/cm2is recommended for safe and effective laser angioplasty.