To date, Parkinson's disease tends to have been perceived mainly as a disorder affecting the extrapyramidal motor system and leading to tremor, bradykinesia, rigidity, and - in later stages - postural instability. However, it is now apparent that patients frequently experience additional clinical symptoms, such as pain, autonomic and sensory dysfunction, neuropsychiatric disorders and sleep disorders. These symptoms often impair patients' quality of life to a greater extent than the motor symptoms. Treatment of these nonmotor features is mandatory and directly improves quality of life. Unfortunately, hardly any double-blind, randomized, controlled studies are available, with the consequence that most recommendations are not based on the highest level of evidence.