Nonmotor symptoms occur commonly in Parkinson's disease (PD) patients and are frequently under-recognized and undertreated. Symptoms include sleep abnormalities, fatigue, autonomic disturbances, mood disorders and cognitive dysfunction. Early recognition and treatment of nonmotor symptoms in PD is critical to providing optimal management. A new screening questionnaire and the revised Unified PD Rating Scale should assist healthcare providers to better identify and evaluate these symptoms. This article reviews the identification and treatment of nonmotor symptoms in PD.