An excess of self-reported neurological symptoms was found when a group of 46 men exposed to methylene chloride at concentrations below 100 ppm was compared with a non-exposed referent group. A follow-up study was then carried out to see whether there was any evidence of neuropsychological damage in the exposed men. Twenty-nine of the original group participated in this study. Age-matched controls controls were selected from among men working on a similar process but with no exposure to solvents. Each man in the study had a clinical examination; motor conduction velocities were measured in the ulnar and median nerves; an ECG was taken and a psychological test battery was designed to detect minimal brain damage was administered. No evidence was found of long-term damage that could be attributed to exposure to methylene chloride.