The purpose of this study was to evaluate the psychometric properties of the Hospital Anxiety and Depression Scale (HADS) in patients with Parkinson's disease (PD) and to assess the prevalence of symptoms of anxiety and depression in this population. The HADS was sent to 205 patients with PD, together with three quality-of-life (QoL) instruments, i.e. the Parkinson's Disease Questionnaire (PDQ-39), the EQ-5D, and a visual analogue scale (VAS). Hospital Anxiety and Depression Scale scores were also compared with Hoehn-Yahr (H&Y) scores. Eighty-six percent of the patients returned the questionnaires. The quality of the data was good. Cronbach alpha for the HADS was 0.88. Test-retest reliability over 2 weeks was 0.84 for the sum score of the HADS (intraclass correlation coefficient) and ranged from 0.42-0.76 for individual items (weighted kappa). Factor analysis revealed two factors, accounting for 51.9% of the variance. One factor represented anxiety, the other depression. Correlations with PDQ-39, EQ-5D, VAS, and H&Y were 0.72, -0.59, -0.59, and 0.32, respectively (p values < 0.001). Depression scores accounted for 52% of the variance in QoL, whereas disease severity explained 24%. Using the cut-off values proposed by the developers indicated that possible and probable anxiety were present in 29.4% and 19.8% of the patients, respectively. Percentages for possible and probable depression were 21.5 and 16.9. The psychometric performance of the HADS in patients with PD is satisfactory. In addition, almost 50% of the patients displayed symptoms of anxiety, whereas nearly 40% showed signs of depression.