The prevalence of tinnitus was studied in a large population of noise-exposed workers. It was found that 6.6% had tinnitus which was more than momentary. Results of two other studies were compared. Factors possibly relating to the prevalence of tinnitus were studied. The single most important factor found to be related to tinnitus is hearing level. The higher the hearing level, the faster the rate of increase in the prevalence of tinnitus. Other factors such as sex, age, laterality, smoking and shooting do not seem to have a significant, direct relationship with tinnitus, but they are related to the prevalence of tinnitus indirectly through the influence they have on hearing loss.