This program initially developed laser microsurgical techniques centered on ophthalmological applications (pulsed carbon dioxide lasers and pulsed ND:YAG slit lamp-based laser systems). Its primary focus for the last seven years, however, has been in cardiological applications, in particular laser angioplasty and the development of pulsed, solid-state infrared lasers for microsurgery. We demonstrated the feasibility of transmission through flexible fiber optics of pulsed IR, visible and UV lasers, and the tissue responses to these lasers. In particular, we have measured the dependence of acoustic transients and ablation efficiency on increasing pulse fluence with catheter systems used clinically, and have concluded that acoustic transients play a dominant role in the clinical results of pulsed laser angioplasty. New IR laser sources were developed in conjunction with the Naval Research Lab and Quantronix Corp. which utilize strong water absorption and can be transmitted through low-loss, cladded optical fibers. Clinical trials were completed of peripheral and coronary laser angioplasty, using either pulsed-dye or pulsed infrared lasers with computer-controlled fluorescence guidance. Recent work has involved identification of the tissue and biological effects of pulsed lasers, particularly the large role that acoustic transients and transient, moderate (approximately 60 degrees C) thermal elevations play in acute and chronic clinical responses. Since pulsed laser angioplasty principally disrupts the atheroma at stenoses mechanically rather than ablating or removing it, optimization of clinical results must be balanced against increased rates of dissection.