In this issue the development of a portable system for measuring fluorescence and reflectance signals of biological tissue is presented. It includes a mini-spectrometer HR4000CG-UV-NIR, with a working range from 200 to 1100 nm and a resolution of 0.5 nm. A light emitting diode at 365 nm with maximum radiant power of 230 mW was used as an excitaton source. A bifurcated fiber optic with six 400 um diameter irradiation fibers and one 400 um collection fiber is used. The system is powered and controlled by a laptop, avoiding the use of an external power supply. A program to control the light source and to measure the spectra in real time was developed using LabVIEW. Preliminary results of ex vivo and in vivo fluorescence measurements of skin and brain tissues are presented and show that fluorescence and reflection could be used to diagnose and demarcat cancer boundaries.