Until effective treatment with levodopa became available in the 1960s, profound akinesia and speech difficulties limited evaluation of the mental state of Parkinson’s disease patients and psychiatric disorders were often unrecognized. This led to the original description of parkinson's disease as a disorder in which “the senses and intellect remain uninjured”. There is now sufficient evidence from numerous objective neuropsychiatric assessment and functional neuroimaging studies that psychiatric disturbances are common and may precede the onset of motor symptoms of Parkinson's disease. The present research was prompted by the paucity data on psychiatric disturbances in Nigerians with Parkinson's disease. Method A cohort of fifty patients with Parkinson's disease and fifty age, sex and the level of education matched controls attending the University College Hospital, Ibadan and the Federal Medical Centre, Abeokuta, Nigeria were studied. The characteristics of Parkinson's disease subjects (age at onset, duration, severity and treatment category) were documented, and the presence of psychiatric symptoms and the subjective distress experienced by their caregivers was determined by quantitative ratings using the Neuropsychiatric Inventory (NPI). Results were compared with those of controls, who are known hypertensive of at least 6 months duration since diagnosis . Socio-demographic and clinical correlates of psychiatric disturbances were identified with univariate and multivariate analysis. Results Relative to age, sex and level of education matched controls, Parkinson's disease patients had significantly more neuropsychiatric symptoms. The mean total NPI domain score of patients with Parkinson's disease was 9.36 (SD 10.57), while that of controls was 3.54 (SD 7.65), with Parkinson's disease patients having significantly more neuropsychiatric disturbances compared to controls p = 0.002. The spectrum of psychiatric disturbances assessed in this study includes delusions, hallucinations, agitations/aggression, depression, anxiety, elation, apathy/ indifference, disinhibition, aberrant motor behaviour, nighttime behaviour and appetite change. Socio_demographic and and clinical correlates of psychiatric disturbances include a longer duration of Parkinson's disease, Severity of motor features of Parkinson's disease, and cognitive impairment in patients with Parkinson's disease. After corellation analysis, severity of motor symptoms was the most important corellate of neuropsychiatric disturbances in this cohort of patients ( rho = 0.37, p = 0002). The presence of neuropsychiatric disturbances also corellated significantly with caregivers distress (rho = 0.80, p = 0.0000). Conclusion Psychiatric disturbances occur more frequently in Nigerian patients with Parkinson's disease compared to age , sex and level of education matched controls. The presence of psychiatric disturbances is associated with caregivers distress. Severity of motor symptom of Parkinson's disease is the most important corellate of of psychiatric