The functional microcirculatory system of the meniscus was investigated in nine sheep using laser Doppler flowmetry (LDF). The highest blood flows recorded were found at the periphery and at the anterior and posterior horns, and this finding was confirmed by india ink injections in five sheep and by meniscal autoradiographs following intraatrial injection of 20 million Cs46 microspheres in four sheep. LDF provides accurate and reproducible assessment of meniscal blood flow. If adequate probes can be developed, this method offers great promise in the clinical assessment of blood flow within the substance of meniscal tears, thus offering the surgeon initial information in the decision to repair or resect a meniscal tear.