The values of clinical tests in general use were calculated in a group of patients who were not selected in advance as suffering from meniscal damage. Arthroscopic examination was employed to control the diagnosis. Employing Smillie's, Bragard's and McMurrays's tests, it was possible to exclude meniscal lesions with 75-95% probability and these could be demonstrated with 25-60% probability. Böhler's test was not correlated significantly with meniscal lesions and the true positive nosographic frequency of Apley's and Jones' tests were so low that their value was limited.