A nylu laser Dopplprflowmrter, based on a personal computer with a digital signal $n-ocessosfor detecting the blood pe$sion in skeletal mu&, was designed and e-valuated. An infrared laser diodp (750 nm) fed a sin@2 optical fibre, 400 pm in diameter, which was introduced into the muscle. A PC equipped with a digital processing unit was used for emulation of the laser Doppler algon'thm and for presentation of the measurement results. The Doppler siffnal power spectral density and correspondingjow values were visualized on the computer screen continuously in rea& time, and could also be saved on the hard disk for ?fUinr analyses. The graphic-user inte$ace sup@-rted by Labwindows software made the system easy to use. It is possible to alter in the sojware the signal processing and the u1ay.c in which the signals and results are presented. The new system was evaluated 4 using a flow model as well as a mechanical model. The model studies showed linear relationships between particle velocity and flow in the range of O-5 mm 3~'. The system was also tested in measurement.r of the blood flow in the brachioradial muscle, and was Jound to have advantages over our jn-eviousJv used .systems. CoBtight