Symptoms of urinary dysfunction occur frequently in patients with Parkinson's disease (PD), particularly men. Irritative symptoms, such as frequency, urgency, and urge incontinence, are reported in 57-83% of patients with PD. Obstructive symptoms, such as hesitancy and weak urinary stream, may be present in 17-36% of individuals. The appearance of urinary symptoms may follow the appearance of motor symptoms by a few years. Several mechanisms, such as detrusor hyperreflexia, detrusor areflexia, coexistent obstructive uropathies, and dysfunction of infravesical mechanisms, can be responsible for the urinary dysfunction in patients with PD. Detrusor hyperreflexia is the urodynamic correlate of irritative urinary symptoms. Detrusor areflexia is uncommon in PD and, when present, is usually secondary to the use of anticholinergic medications. Coexistent obstructive uropathies may complicate the clinical picture in patients with PD and produce both obstructive and irritative symptoms. Urinary dysfunction in PD also may be the result of dysfunctional infravesical mechanisms such as sphincter bradykinesia. In terms of pathogenesis, voiding dysfunction in PD is primarily due to the loss of the inhibitory effect that the basal ganglia exert on the pontine micturition center. This inhibitory effect likely is mediated by D1 dopamine receptors and results in a "quiet bladder" during the filling phase. In terms of treatment, the irritative symptoms often can be treated successfully with anticholinergic drugs; however, for refractory overactive bladder, intravesical botulinum toxin injections or deep brain stimulation surgery may be required. If the symptoms are obstructive in nature, bladder catheterization and sometimes urological surgery may be necessary.