Using a real time scanner and a 7.5 mHz transducer, the meniscus can bei visualised as a homogeneous triangle. It is clearly distinguishable from the tibial plane und the condyle of the femur. Tears in the meniscus show up as a double contour rich in echoes with an intervening low-echo area, or as a contour rich in echoes with an adjacent low-echo area. The posterior horn area can be visualised most clearly. Assessment of the interior part of the meniscus is somewhat easier than visualising the exterior part. In a clinical study with 107 menisci examined by sonography and controlled by arthroscopy or arthrotomy the rate of accurate diagnoses by sonography of the meniscus is 82%. 42 of these menisci were additionally examined by double contrast arthrography besides sonography. This yielded an accuracy rate of 74% for double contrast arthrography; the latter is superior to sonography only in the anterior horn area. Problems in respect of meniscus sonography occur only in case of transverse ruptures, scars and longitudinal meniscus ruptures presenting as bucket handle tears near the base. The typical longitudinal tear in the area of the posterior horn can be visualised most clearly. Analysis of the results shows that sonography of the meniscus is a noninvasive, painless and randomly reproducible and risk-free examination method which has a diagnostic value especially in the area of the posterior horn that can be compared with double contrast arthrography. Further studies must show whether with an increasing spread of the method it would be possible to replace double contrast arthrography by sonography in diagnosis of menisceal trouble.