AbstractMost previous occupational health studies have employed various questionnaires for the quantitative assessment of mental symptoms. However, reporters' errors may reduce the value of the information so obtained. Semistructured psychiatric interviews and rating scales offer another method to collect data on the prevalence of mental symptoms. This paper describes the application of rating techniques in an epidemiological study of the effect on the nervous system of occupational exposure to organic solvents. The results suggest that ratings by trained interviewers are as useful as many neurophysiological and psychometrical methods to detect early neurotoxicity. The contention agrees with a general opinion that slight changes in mental comfort and personality often are the first signs of progressive brain damage.