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.