OBJECTIVE To investigate change of high frequency (UHF) threshold in patients suffering from tinnitus but with normal pure threshold. METHODS High frequency audiometry was carried out on 48 tinnitus patients with normal pure shreshold and 30 young students with normal pure shreshold but without tinnitus as a control group. Then the patients were divided into three groups according to the age: < or = 25 years old, 26-35 years old and 36-45 years old. The hearing loss were statistically analyzed between the three groups and the control. RESULTS The results showed very significant differences of HF threshold between ipsilateral ear (tinnitus ear) in three groups and that in the control group, P < 0.01; very significant differences of HF threshold between ipsilateral ear (tinnitus ear) and that of contralateral ear (no tinnitus ear) in each group, P < 0.01; no significant differences of HF threshold between ipsilateral ear (tinnitus ear) in the age of < or = 25 years old and between 26-35 years old, P > 0.05. CONCLUSIONS HF audiometry should be carried out on patients who are suffering from tinnitus but with normal hearing sensitivity, because their HF threshold may be abnormal. The change of HF threshold may be related to aging. The start age may be at about 30 years old.