This work describes the implementation of a compact system allowing measurement of blood flow velocity using laser Doppler velocimetry in situ. The compact setup uses an optical fiber acting as an emitter and receptor of the signal. The signal is then recovered by a photodiode and processed using a spectrum analyzer. The prototype was successfully tested to measure microbead suspension and whole blood flow velocities in a fluidic chip. Fibers with hemispherical lenses with three different radius of curvature were investigated. This simple yet precise setup would enable the insertion of the fiber via a medical catheter to monitor blood flow velocity in non superficial vessels where previous reported techniques cannot be implemented.