Although urinary disturbances are more frequent in multiple system atrophy (MSA) than in Parkinson's disease (PD), the striatonigral degeneration (SND) type of MSA is difficult to distinguish from PD, especially when the latter is associated with orthostatic hypotension or urinary symptoms. The pattern of urinary symptoms and urodynamic dysfunction was analyzed in 15 SND and 35 PD patients with urinary complaints. In SND, dysuria with or without chronic retention, frequently associated with a hypoactive detrusor and low urethral pressure, permitted early and reliable diagnosis. In PD, urgency to void, with or without difficulty voiding, but without chronic retention, associated with detrusor hyperreflexia and normal urethral sphincter function, predominated. In clinical practice, the study of urinary symptoms and bladder function may help to distinguish SND from PD in patients with urinary disturbances.