In reviewing the literature, tinnitus is an otologic phenomenon which vague origin and multiple characteristics can be only inferred. In addition, exact causes and effective treatment have been eluded otolaryngologist so far. Despite its elusiveness, tinnitus appears to be interesting subject as evidenced by voluminous literature concerning it. So much has been reported regarding objective tinnitus, which is rather a rare type of tinnitus, but only a few report has dealt about subjective tinnitus. The auther, therefore, tried to have an analysis of subjective tinnitus cases generally known as true tinnitus on the aspects of physiological origin, clinical characteristics and effective treatment. This paper deals 91 cases of subjective tinnitus, who visited the otolaryngological clinic of Yonsei Medical Center during one year of Sept. 1966-Aug. 1967 inclusively and the findings are follows ; 1) Among 1247 cases of ear disease, there were 91 cases of tinnitus (7.4 per cent). 2) The sex ratio between male and female was 1.2 to 1. 3) The average age of the patient was 38.1±2.1 yrs. with the range of 11 yrs. to 69 yrs. and 36.8±1.8 yrs. in male, 39.5±3.7 yrs. in female. 4) Acute or chronic inflammation of the ear was the most common cause, followed by drug intoxication, acoustic trauma and the others. 5) The patient had tinnitus of 1906±29 cps. and 13±0.8 db. in average. Most of the tinnitus were continuous in its characteristics by and large, and belonged to low tone. 6) Hearing loss was the most common symptom accompanied with tinnitus and they had 38.8±1.8 db. in air conduction and 23.3±1.2 db. in bone conduction in average. The others were dizziness, fatigue and dull headache in order. 7) Nicotinic acid and 7% sodium bicarbonate as vasodilatator were fairly effective for the treatment of tinnitus.