This paper shows the results of using air as a contrast medium in ultrasonography of the menisci (aerosonography). 100 menisci (50 knees) were examined with aerosonography and in 93 = 93% the findings were proven to be true by subsequent arthroscopy. 6% of the findings were false positive (2 medial menisci and 4 lateral menisci). One false negative finding concerned a lesion at the free inner edge of the lateral meniscus. Not one single lesion of the medial meniscus was totally missed. The sensitivity of aerosonography is 97.8%, the specificity 89.1%. The predictive value is 88%, the accuracy is 93%. Considering the medial meniscus alone the aerosonographic diagnosis proved to be true in 96% (sensitivity for the medial meniscus 100%, specificity 87.5%, predictive value 94.4%, accuracy 96%). 90% of the aerosonographic diagnosis concerning the lateral meniscus were confirmed by arthroscopy (sensitivity for the lateral meniscus 90.9%, specificity 89.1%, predictive value 71.4%, accuracy 90%).