We evaluated the sensitivity and specificity of a screening instrument developed for use in a two-phase neuroepidemiological survey in Sicily. The Sicilian Epidemiological Dementia Study (SEDES) project will evaluate the prevalence and incidence of dementia, parkinsonisms and essential tremor in four Sicilian municipalities. It is a two-phase door-to-door survey. To identify subjects with possible neurological disorders, in this study, we developed a screening instrument including a symptoms questionnaire and simple physical tasks for parkinsonisms and essential tremor. The Mini-Mental State Examination (MMSE) was chosen for screening dementia. The symptoms questionnaire and simple tasks developed to identify possible patients with parkinsonism and essential tremor, was tested in a hospital setting. To evaluate sensitivity, we selected 20 patients with essential tremor and 40 with Parkinson's disease (20 with Stages I-II and 20 with Stages III-V) [Neurology 17 (1967) 427]. To evaluate specificity we also selected 20 healthy subjects. The screening instrument was administered in a hospital setting by trained interviewers. Sensitivity of the screening instrument (questionnaire plus simple tasks) was 100% for essential tremor and parkinsonisms regardless of the stage. Specificity of the instrument was 90% (95% CI 66.9-98.2); the predictive positive value was 90.9%, while the negative predictive value was 100%. Even if validity was assessed in a hospital setting, the high sensitivity and specificity obtained suggest that the instrument could be an appropriate screening tool for parkinsonisms and essential tremor in a two-phase neuroepidemiological survey.