In the clinical routine examination of patients with brain tumors, aphasic symptoms are often not recognized. In order to document the incidence of such symptoms, three diagnostic methods of testing for aphasia were compared: the Aachen aphasia test (AAT), which is the German standard aphasia test, clinical examination, and the Aachen aphasia bedside test (AABT), which was designed to test patients in the acute phases of illness. In the AAT, 50% of patients with left-sided tumors and 36% of those with right-sided tumors showed aphasic disturbances. The AAT results were defined as the gold standard. Clinical examination showed only low sensitivity; less than half of the aphasic patients were diagnosed as such. The AABT also detected only about half of the patients with aphasic disturbances. The low sensitivity is caused mainly by the results of the patients with right-hemisphere tumors, in which the mental set of the examiner during clinical examination (aphasic symptoms are not expected in patients with right-hemisphere lesions) and the pattern of disturbances in the AABT (deficits may be less severe and different in nature) may prevent detection of aphasic symptoms. Both clinical examination and AABT are thus not suitable for aphasia diagnostics in brain tumor patients. As the AAT is very time-consuming in everyday clinical routine, however, the development of an aphasia screening test seems desirable.