Subcutaneous administration of 5 mg. bethanechol chloride did not change significantly either flow rates or percentage residual urine in 11 patients with a positive bethanechol supersensitivity test. Therefore, a positive response to this test cannot be used to predict improved voiding function after subcutaneous or oral administration of the drug. Studies that purport to show a long-term rather than a short-term facilitory effect of this agent on voiding must satisfy rigid criteria, which include totally excluding a change in any other factor affecting the lower urinary tract.