Persons with a history of exposure to organic solvents have been shown to have cognitive and personality changes, as well as abnormalities on measures of neurophysiology (e.g., delays in P300 latency). Studies assessing long-term sequelae in exposed persons have been limited, especially those using neurophysiologic measures. This study assessed cognitive event-related potentials (ERPs) in 16 persons with a history of organic solvent exposure at two testings, separated, on average, by 1.5 years. The sample was divided into persons who showed improvement on P300 latency (e.g., reduction in latency of 1.5 SD of control group) and those who did not. Sixty-three percent showed no improvement, whereas 37% showed significant improvement. Recency of exposure and the interaction of exposure duration and history of peak exposure significantly predicted group membership. That is, persons with shorter duration of exposure coupled with no peak exposures and longer time from exposure to test were more likely to fall in the improved group. Substituting age for duration of exposure in the interaction term improved classification of the two groups. The results support previous findings that most exposed persons do not show significant improvements over time. The results further suggest that there is a need to assess factors, such as aging, which may make one more vulnerable to the neurotoxic effects of solvents.