Very little has been written in the literature about the masking effect of tinnitus on hearing. This possibility arose from the clinical observations of hearing fluctuating with the intensity of tinnitus. To explore this hypothesis, a group of 19 patients suffering from hearing loss and tinnitus underwent a complete audiological evaluation and their audiometric and ABR thresholds were compared. Two other groups who were examined in the same manner, served as control groups. The first group consisted of 19 age- and sex-matched subjects with relatively normal hearing and no tinnitus. The second control group was composed of 8 patients suffering from sensorineural hearing loss without tinnitus. The differences between the subjective and ABR thresholds within each group and between the groups were statistically analyzed. The objective thresholds in the tinnitus group were found to be lower than the subjective thresholds.