This study explores UV light induced fluorescence from blood vessels for indicating successful infrared laser sealing of vascular tissues. A light emitting diode (LED) with center wavelength of 340 nm and 0.1 mW power was used with a Y-shaped fiber bundle of seven 200-μm-core fibers. The central excitation fiber was connected to the LED, while the detection ring of six fibers was connected to a spectrometer. The fiber bundle was aligned with porcine renal arteries compressed between optical windows. Fluorescence was acquired before and after vessel sealing, with a 1470 nm laser for 5 s at 30 W (sealing, n = 10) or 5 W (control, n = 10). Signal increase in the 470-520 nm spectrum was correlated with vessel burst pressures (BP). Integrated fluorescence increased 71 ± 25% at 30 W vs. 19 ± 14% at 5 W (p < 0.05), corresponding to a successful BP of 639 ± 189 mmHg vs. failed seal BP of 39 ± 41 mmHg (p < 0.05). Real-time measurements showed a gradual increase in fluorescence with the signal reaching a plateau at 3-4 s, indicating that shorter seal times are possible. The increase in fluorescence signal during laser vessel sealing may provide a non-destructive, real-time, optical method for indicating hemostatic seals.