The urodynamic findings in 15 patients with voiding dysfunction associated with various forms of the ataxia syndrome were reviewed. Urodynamic studies helped segregate the patients into 3 groups: group 1-detrusor hyperreflexia, group 2-normal bladder contractility and group 3-acontractile bladder. Pelvic floor electromyography demonstrated either coordinated or uncoordinated vesicosphincteric function. Although the neurologic findings associated with the ataxia syndrome have been studied extensively the urodynamic findings have not yet been recorded. We emphasize the importance of urodynamic evaluation in the treatment of patients with ataxia and voiding dysfunction.