Background: The cause of sudden sensorineural hearing loss (SSNHL) is still unknown. Literature has indicated that there is a statistically significant correlation between hyperhomocysteinemia and SSNHL, yet there is lack of study in the relationship concerning total frequency deafness subtype of SSNHL. This study investigated the relationship between plasma concentration of homocysteine (Hcy), serum concentration of folic acid and occurrence and treatment responding in total frequency deafness adult patients, and explored whether targeted early intervention was associated with improved clinical outcome in this subgroup. Methods: A total of 54 consecutive adult patients with diagnosis of sudden total frequency deafness in a single institution was enrolled into the study group. Two control groups were established. Control group 1 was derived from inpatients with normal listening comprehension. Control group 2 included 52 patients with sudden total frequency deafness treated in a parallel hospital. Blood concentration of folic acid and Hcy was investigated. Treatment included Ginkgo biloba extract, dexamethasone, hyperbaric oxygen, folic acid, vitamin B6, and optional vitamin B12. All data was statistically analyzed. Blood level of Hcy and folic acid was compared between study group and control group 1. Results: Although there was no clear evidence for the divergence trend of Hcy and folic acid levels individually, the results showed that the study group had higher blood level of Hcy and lower blood level of folic acid, than control group. In the study group, 24 patients (44.44%) demonstrated treatment effectiveness after the 2-week treatment course. Patients without vertigo had higher effective rate than patients with vertigo (P<0.05). Conclusions: Effective rate of study group was higher than control group 2 which had no folic acid and vitamin B6/B12 supplement. High blood Hcy and low blood folic acid were closely associated in patients with sudden total frequency deafness. The currently accepted concept of treatment for sudden total frequency deafness is not essentially satisfactory. Testing of plasma Hey and serum folic acid may provide referential value for its treatment and prognosis evaluation.