The objective of this study is to determine the prevalence and factors associated with psychosis in Parkinson’s disease (PD) patients. Method: This is a cross-sectional study of 108 PD patients from neurological clinic UKM Medical Centre and Kuala Lumpur Hospital. The patients were recruited from August to December 2004. Psychosis was determined using SCID, the severity of psychosis was rated using BPRS. The cognitive functions were evaluated with MMSE and the severity of depression was assessed with HAM-D. Results: The result shows that the prevalence of psychosis in Parkinson’s disease patients in this sample was 13%. The psychosis was found to be significantly associated with advancing age, duration of illness, severity of depression and cognitive impairment. Multivariate analysis demonstrates that severity of depression (OR = 1.08, 95% C.I. = 1.01 – 1.16) and advancing age (OR = 4.72, 95% C.I. = 1.37 – 16.29) increased risk of psychosis in PD patients. Conclusion: We found that advancing age and severity of depression increase risk to develop psychosis in patients with PD.