The continuous expanding of CO2 laser applications in medicine needs not only compact, reliable and multifunctional surgical CO2 laser units, but also specialized beam delivery systems, which are essential to extend the clinical use of lasers. Our effort for improving the surgical CO2 laser units was directed to : a) developing compact CO2 laser scalpels, reliable and more suitable for the surgical operating theatre by using high performance with low maintenance average power sealed-off CO2 lasers; b) designing specialized electronic circuits to increase the protection degree against uncontrolled irradiation by technical failures or wrong manipulation; c) extending the operating regimes, i.e. continuous wave, laser pulses with pre-established length and laser pulses with variable repetition frequency. The beam delivery systems used with our surgical CO2 lasers units included opto-mechanical articulated arms, IR fiber optic cables and laser microscope adaptors. Coupling different CO2 laser scalpels, beam delivery systems and terminals, we have tested these surgical laser units in neurosurgery, otolaryngology,,ophthalmology and microvascular lympho-venous anastomosis. The most significant data recorded by us on the interaction of laser radiation with living matter are shortly reviewed.