We performed a survey on diagnosis and treatment of Idiopathic Sudden Sensorineural Hearing Loss (ISSHI) and report the opinion of 230 Dutch and 50 Flemish ENT-surgeons. Questions concerned definition, incidence, diagnosis, therapy and possible etiology of ISSHL. Considerable disagreement exists on ISSHL. The incidence of ISSHL varied with the preciseness of its definition. We found shortcomings in diagnosis of ISSHL and recommend the use of a diagnostic protocol based on a differential diagnosis. Therapy of ISSHL often lacked scientific foundation and treatment results were comparable to the spontaneous recovery rate of ISSHL. We recommend treatment of ISSHL to take place in a carefully designed clinical trial.