The non-motor symptoms of Parkinson's disease, which include cognitive, behavioural and psychological problems, are significant not just in epidemiological terms but also in their impact on patients and carers. Each symptom requires careful evaluation, owing to the potential overlap with comorbid conditions and also to the multiple aetiological pathways in Parkinson's disease. Such monitoring allows enhanced management. However, the diagnostic difficulties arising from these non-motor symptoms require further research. Here we describe the efficacy and some of the problems of medication used for non-motor symptoms, including antiparkinsonian medication, antipsychotics and acetylcholinesterase inhibitors.