Laser-induced fluorescence spectroscopy has been used for the detection of advanced atherosclerotic lesions. Angioplasty balloon-mediated injury was examined spectroscopically in order to assess the sensitivity of fluorescence spectroscopy for detection of early atherosclerosis. Abdominal aortic balloon angioplasty was performed via femoral artery cutdown in nine White Leghorn roosters (five normal, four atherogenic diet). Roosters were sacrificed at 1, 2, 4, 8, and 12 week intervals. Fluorescence emission spectra (n = 114) were recorded from each aortic section (XeCl excimer laser, 308 nm, 1.5 - 2.0 mJ/pulse, 5 Hz). Changes in normalized fluorescence emission intensity were correlated with selected sections of histology. All balloon-injured segments showed intimal fibrous proliferation. For intimal thickness measuring > 70 μ, fluorescence emission intensity was decreased at 440 - 460 nm (p < 0.0005). Lesions complicated by thrombus also had lower fluorescence emission at 425 - 450 nm when compared to histologically normal aorta (p < 0.009). In injured segments high cholesterol diet resulted in lower recorded fluorescence emission at 440 - 460 nm (p < 0.001) associated with the increase in intimal thickness. Spectra from uninjured elastic aorta (aortic arch and thoracic aorta) had greater fluorescence intensity at 380 - 445 nm than muscular (abdominal) aorta (p < 0.01), therefore, only spectra from injured and uninjured segments of corresponding areas of the aorta were compared. The conclusion is: (1) Early intimal proliferative changes after angioplasty can be detected by fluorescence spectroscopy. (2) Spectra from elastic thoracic aorta differ significantly from the spectra of muscular abdominal aorta.