Cyclandelate is a vasodilating agent that, like papaverine, acts directly on the smooth muscles of blood vessels. The drug has been used primarily as an adjunctive treatment for various peripheral vascular diseases; some studies advocate its use for treating ischemic cerebrovascular disease. Early nonrandomized and uncontrolled studies suggest that cyclandelate is efficacious in treating tinnitus. Recent personal communications regarding cyclandelate's effectiveness in treating tinnitus prompted this study. Fifty-nine adult patients with constant tinnitus for more than 1 year were randomly selected for this prospective, placebo-controlled, double-blind study with a treatment period of 3 months. Audiometric testing with tinnitus pitch and loudness matching was performed before initiation of treatment and at the end of treatment, and frequent questionnaire evaluations were performed during the treatment period. Four patients in the cyclandelate group and three in the placebo group reported a subjective reduction in the loudness of their tinnitus. Audiologic testing before and after treatment showed no significant changes in tinnitus pitch or loudness. Although cyclandelate treatment was beneficial for some patients and the decrease in subjective loudness scoring was significant for the cyclandelate group, the impact of its effect did not appear to warrant its continued use by those patients. A significant percentage of patients could not tolerate the drug because of side effects.