The aim of this study was to investigate the effects of n-hexane on visual function and to determine the duration of any symptoms related to workplace exposure. The study involved 26 workers diagnosed as having polyneuropathy following n-hexane exposure. The FM-100 Hue test was used to determine colour discrimination in study volunteers. Their results were compared with a control group of 50 people who had not been exposed to n-hexane. The mean total error score for the exposed group was 168.3 (SD = 70.5) for the right eye and 181.5 (SD = 103.0) for the left eye. The mean total error scores for the control group for the right and left eyes were 36.0 (SD = 19.8) and 35.6 (SD = 18.2), respectively. Differences between total and partial error scores for exposed and control groups were statistically significant (P < 0.001). These results may indicate a relationship between n-hexane exposure and development of defects in colour vision, and would support a recommendation for periodic assessment of workers exposed to n-hexane and chemically related solvents.