From all methods of the treatment of tinnitus, medical, masking, surgery, electrical stimulation and psychological, we believe a reliable medical treatment would be preferable because it is easy to apply. An immense variety of drugs have been used for the treatment of tinnitus (Vernon, 1977). The most reliable drugs so far on tinnitus are intravenous procaine and lidocaine (Bárány, 1935; Lewy, 1937; Melding et al., 1978; Martin and Colman, 1980; Israel et al., 1982). The fact that these drugs cannot be given orally because of the poor biological availability after oral administration, is a great disadvantage. In view of the important pharmaco-therapeutic role of lidocaine as an anti-arrhythmic drug, considerable research has been devoted to drugs with comparable anti-arrhythmic properties but permitting oral administration. This work produced tocainide (Smith, 1981), which showed a certain degree of effect on tinnitus as well (Emmett and Shea, 1980; Cathcart, 1982). Before starting a randomized double-blind controlled trial to assess the effect on tinnitus of tocainide, we studied the effect of several doses of tocainide HCl on tinnitus in order to select an appropriate dosage. Nineteen patients with obstructive tinnitus of various aetiologies were admitted to the study. There were 10 women and nine men. Their mean age was 54 years (range 22–67 years). Tocainide was administered in five different doses in a single-blind controlled trial. To be able to judge the effect under steady conditions, each dose was given for four days, as shown in Table I. On the fourth day of each period the patients had to record the degree of impediment caused by the tinitus on a six-point scale (Table II). They were also asked to report all sideeffects.