Symptoms and signs were recorded in a series of 78 patients with a cerebello-pontine-angle (CPA) tumour and in 92 patients with symptoms and signs suggestive of such a lesion but with a negative CT scan. Variable symptomatology was found in the tumour cases. A substantial proportion of the patients had experienced sudden phenomena such as rotatory vertigo and/or sudden hearing loss. A CPA tumour must therefore be considered in almost every case of unilateral auditory or vestibular disturbances. Unfortunately, conventional audiovestibular tests have a low sensitivity of around 50%, with the exception of stapedial reflex threshold elevation (89%). The specificity on the other hand is quite low for this test, whereas other test results, like a genuinely pathological stapedial reflex decay, carry a high specificity of 60%. However, brainstem response audiometry (BRA) exhibited a very high sensitivity (100%) coupled with a reasonable specificity (54%), making it a suitable single test for screening patients suspected of having a CPA tumour. A program for the diagnostic work-up is suggested.