This retrospective study characterized the P300 component of the auditory event related potential (ERP) and assessed its diagnostic value in occupational chronic solvent encephalopathy (CSE). The P300 was recorded on 86 CSE patients by the classical oddball paradigm. In addition to the laboratory's reference values, we used an age and education matched control group that consisted of 104 blue-collar workers with no known occupational solvent exposure. The association of P300 values with solvent exposure indices, major depression, alcohol consumption, and neuropsychological parameters was studied. The P300 amplitude was lower in CSE patients (mean 7.5 microV; S.D. 3.6) compared to laboratory controls (mean 11.8 microV; S.D. 4.1; F(1,167)=24.4; p