The effect of two parasympatholytic drugs, trospium chloride and hyoscine-N-butylbromide, was studied by urodynamic tests in 20 patients with spastic neurogenic bladder function. After intravenous injection of 0.6 mg trospium chloride or 60 mg hyoscine-N-butyl bromide bladder capacity increased significantly, while the degree of spasm and the response in the ice water test decreased significantly. Maximal sphincter pressure, resting bladder pressure, maximal bladder filling pressure and abdominal pressure remained unchanged.