In 5 patients with multiple system atrophy, administration of 15 mg/day of amezinium metilsulfate, an adrenergic agent, during 6 months for the treatment of postural hypotension exacerbated post-micturition residuals as compared to that before treatment (178 ml versus 113 ml for a change of 37 %, p < 0.05). Amezinium metilsulfate most probably stimulates both alpha1B-receptors in the vascular wall and alpha1A/D-receptors in the proximal urethra.